Once Batman has reappeared on the screen, you will have to start walking to the right and collect a Gas Grenade for fifteen more shots of it as a brown-suited gangster and a gray-suited gangster come walking towards you while firing shots and throwing gas bombs at you; once you have thrown two Gas Grenades at both of them to kill them you will have to jump up and throw two more Gas Grenades at two green-jacketed thugs (who have emerged from a door on the first floor) to kill them. You will now have to throw a seventh Gas Grenade at a third green-jacketed thug to kill him before he has a chance to pick up a sculpture and throw it at Batman - and once you have done so you will have to jump up and throw two more Gas Grenades at another gray-suited gangster who has emerged from a second door on the first floor and another brown-suited gangster on the same floor to kill them. A red-jacketed thug will now burst out of a painting and come running towards Batman while wielding a knife - and once you have thrown a twelfth Gas Grenade at him to kill him you will have to throw a thirteenth Gas Grenade at one of the Joker's jack-in-the-boxes to destroy it (it is worth 200 points). You will now have to jump up to the first floor, and continue walking to the right for twenty-four extra seconds; there are also no Bat-Symbols for extra energy in this stage.
Four brown-jacketed thugs, three more brown-suited gangsters, and a third gray-suited gangster emerge will then from seven more doors; once you've thrown a single Gas Grenade at each of the thugs to kill them (and two at each of the gangsters), you shall have to jump back down to the ground floor and throw three more Gas Grenades at three more of the Joker's jack-in-the-boxes, to destroy them. Once you've done so, you'll have to jump back up onto the first floor and collect a Batarang for fifteen shots of it - and once you've done so you shall have to drop down onto a fifth of the Joker's jack-in-the-boxes to destroy it. A fifth brown-jacketed thug will now emerge from a tenth door on the first floor; once he's jumped down to the ground floor, and you've thrown a Batarang at him to kill him (killing them this way is only worth 480 points), two more gray-suited gangsters shall come walking towards you, while throwing gas bombs at you (and a sixth one on the first floor jumps down to the ground one). Once you have thrown two more Batarangs at each of them to kill them, a fourth green-jacketed thug will emerge from an eleventh door on that first floor - and once he's jumped down to the ground floor and you have thrown an eighth Batarang at him to kill him, another red-jacketed thug will burst out of another painting and come running towards Batman with a knife. Once you have thrown a ninth Batarang at him to kill him, a fifth green-jacketed thug will jump down to the ground floor from that first one; once you have thrown a tenth Batarang at him to kill him a red-shirted gunner will come walking towards you while firing shots at you (which Batman must jump up to that first floor to avoid). Once you have thrown four more Batarangs at him to kill him (he is worth 50 points for the first three hits and 800 for the fourth), a third red-jacketed thug will emerge from a third painting and come running towards Batman while wielding a knife - and once you have thrown a fifteenth (and final for now) Batarang at him to kill him you will have to jump back up to the first floor and collect another Gas Grenade for fifteen more shots of it. Another red-shirted gunner will then come walking towards you, while firing shots at you (which Batman will now have to jump down to the ground floor to avoid); once you've thrown four Gas Grenades at him to kill him, you'll have to throw a fifth one at a sixth of Joker's jack-in-the-boxes to destroy it. Three of the Joker's gas balloons will then come floating towards you - and once you have kicked or punched each of them at close range to destroy them (they're worth 400 points), you have to continue walking to the right for twenty-four more extra seconds.
You shall then come to a fourth of the Joker's gas balloons, that is moving up and down; once you have kicked or punched it at close range to destroy it, you will have to collect another Batarang for fifteen more shots of it. You will then come to three more of the Joker's gas balloons that are moving up and down - and once you kick or punch each of them at close range to destroy them, three more of the Joker's gas balloons shall come floating towards you, as they zigzag up and down. Once you have kicked or punched each of them at close range to destroy them three more brown-jacketed thugs will come walking towards you; once you have thrown three more Batarangs at each of them to kill them, four more of the Joker's gas balloons shall come floating towards you. Once you've kicked or punched three of these at close range to destroy them (the fourteenth one can be walked under after that), a fourth red-jacketed thug will come running towards you while wielding a knife - and once you have thrown a fourth Batarang at him to kill him, you will come to two more of the Joker's gas balloons that are moving up and down. Once you have kicked or punched both of them at close range to destroy them, two more brown-suited gangsters will come walking towards you, while firing shots at you; once you have thrown two more Batarangs at both of them to kill them, you'll have to jump back down to the ground floor and collect a third Batarang, for fifteen more shots of it, then turn back to the left and throw two more Batarangs at an eighth brown-suited gangster to kill him. Once you've done so two more brown-suited gangsters shall come walking towards you while firing shots at you - and once you have thrown two more Batarangs at both of these to kill them you shall have to continue walking to the right for twenty-four more extra seconds (you must also not take too long over killing the enemies while playing it safe here because you might run out of time).
You will then have to jump back up to the first floor and collect a third Gas Grenade for fifteen more shots of it and throw a Gas Grenade at a seventh of the Joker's jack-in-the-boxes to destroy it; once you have done so, a ninth brown-jacketed thug shall emerge from a twelfth door. Once you have thrown another Gas Grenade at him to kill him, you'll come to three more of the Joker's gas balloons, that are moving up and down - and once you have kicked or punched each of them at close range to destroy them you shall have to drop down onto an eighth of the Joker's jack-in-the-boxes to destroy it. Three more red-jacketed thugs shall now come running towards you while wielding knives; once you have thrown a Gas Grenade at each of them to kill them, an eighth red-jacketed thug shall emerge from a thirteenth door on that first floor. Once you've jumped up and thrown a sixth Gas Grenade at him to kill him you will have to jump up and throw two more Gas Grenades at a ninth of the Joker's jack-in-the-boxes on the first floor to destroy it and a ninth red-jacketed thug on the same floor to kill him - and once you have done so, a tenth red-jacketed thug will come running towards you while wielding a knife. Once you've thrown a ninth Gas Grenade at him, to kill him, you shall have to throw a tenth one at a tenth of the Joker's jack-in-the-boxes, to destroy it; once you've done so, you will have to jump up, and throw three more Gas Grenades at three more red-jacketed thugs on the first floor to kill them. You then have to jump back up to the first floor (and collect a fourth Batarang for fifteen more shots of it) - and once you've done so, three more gray-suited gangsters will come walking towards you, while throwing gas bombs at you. Once you have thrown two Batarangs at each of them to kill them, you will have to continue walking to the right for eighteen more extra seconds; if sent back here without a weapon, this stage will become very difficult to finish.
Two more red-jacketed thugs will then emerge from two more doors and come running towards Batman while wielding knives; once you have thrown a Batarang at both of these to kill them, two more of the Joker's gas balloons shall come floating towards you. Once you have kicked or punched both of them at close range to destroy them you will have to collect a fourth Gas Grenade for fifteen more shots of it - and once you have done so, a sixteenth red-jacketed thug will emerge from a sixteenth door, and come running towards Batman while wielding a knife. Once you've thrown a Gas Grenade at him to kill him you will have to throw another one at an eleventh of the Joker's jack-in-the-boxes to destroy it; once you have done so, you will come to the Joker himself, who shall say The pen, is truly mightier than the sword! from the MSM-6295 as he throws pens and fires shots at Batman (which he must either crouch down or jump to avoid). Once you've thrown eight more Gas Grenades at him to make him retreat (he is worth 200 points for every hit) and cackle Heh-heh-heh-heh-heh-heh-heh! from the MSM-6295, you'll have to continue walking to the right towards Vicki Vale - and once Batman has reached her, he will say Hold on. from the MSM-6295 as a flying fox appears, they both go down it together to exit the museum as the Joker says Where does he get those wonderful toys? from the MSM-6295 off-screen (you meet him again four stages later), and you receive a 2500-point bonus.
Note: The timer still goes while Batman goes down the flying fox with Vicki Vale, and if it runs out before he exits the museum he will immediately die.