Island 21[edit]
This island is identical to the twentieth one so you shall have to go back to Trog/Islands 11-20#Island 20 to remind yourself of all the information about it.
Island 22 (Bonus Stage)[edit]
On this island, the text "BONUS WAVE. BARBECUE! SMOKE 'EM ALL! (YOU HAVE 20 SECONDS)." will appear upon the screen as the "HOME base open" theme starts to be heard from the Yamaha YM-2151 and twenty-four Brown Trogs emerge from the ground and start running around the island in terror (the triceratopses will all have forcefields here, so they cannot get killed). If you manage to burn all twenty-four of the Trogs between you, the text "YOU ARE HOT! 100,000 POINTS FOR EVERYONE." shall appear on the screen (but if you do not, the text "TIME IS UP!" shall appear instead) - and after this stage, you shall all get treated to the third "Trogs' Cave" cutscene, which depicts a Brown Trog carving a picture of one of his fellow tribesmen smashing through a bone (which has a triceratops on the other side), onto the cave wall, then imagines himself hitting one of the triceratopses over the head with a club. The carving refers to the original prototype version of the game, which is dated Friday 27th July 1990; in this abandoned concept, the players had no control over the triceratopses, and instead would have controlled hands who had to place bones in their path to guide them to the eggs.
Island 23[edit]
This island happens to be identical to the third one, so you'll have to go back to Trog/Islands 1-10#Island 3 to remind yourself of the information about it.
Island 24[edit]
On this island, there are thirty-two eggs (for a 17th time, of each colour, if you are not playing it alone; if Bloop or Spike are present, the eggs in the top-right and bottom-left corners will again not be there, and if Rex is not present, there will be one in the top-left corner), only Brown Trogs, and a big hole.
Island 25[edit]
This island happens to be identical to the fifth one, so you'll have to go back to Trog/Islands 1-10#Island 5 to remind yourself of the information about it.
Island 26[edit]
This island happens to be identical to the ninth one, so you'll have to go back to Trog/Islands 1-10#Island 9 to remind yourself of the information about it.
Island 27[edit]
This island is identical to the thirteenth one, so you will have to go back to Trog/Islands 11-20#Island 13 to remind yourself of all the information about it.
Island 28[edit]
This island is identical to the seventeenth one so you'll have to go back to Trog/Islands 11-20#Island 17 to remind yourself of all the information about it.
Island 29[edit]
This island is identical to the 18th and 19th ones, so you'll have to go back to Trog/Islands 11-20#Islands 18 and 19 to remind yourself of its information.
Island 30[edit]
This island is identical to the 20th and 21st ones, so you will again have to go back to Trog/Islands 11-20#Island 20 to remind yourself of its information.