M.C. Kids/Professor's Workshop

As soon as you arrive at Professor's Workshop, he will show the kids a rocket of his own invention, thanks to which you can reach the moon, where you can find clues as to where Hamburglar has escaped. Before letting you go, however, Professor will ask you to find at least five cards of his puzzle (at this point you should already have collected two).

Level 1 - Ports o' Comets
Walk to the right, paying attention to the meteors. After jumping over the first gap, jump over the narrow blue pillars. Even if they just appear to be part of the background, you can in fact jump on them. This way, with a few long jumps to the left, you'll reach a row of blocks with five 1-Ups! Then go right and grab one of the floating blocks. Immediately after, you will find a super springboard. Thanks to the block you have collected, you can make a very high jump and reach a card in the sky: jump on it and take it. Further to the right you will find the finish line. However, you will have to take a long jump and overtake it. Below, on the right, you will find a boat. Jump into it and go through the whole level backwards, paying attention to the fish. At the end you will find a card to collect and a zipper. Enter the zipper to access a bonus area. You will notice three paths, all filled with sand to be excavated. However, there is a fourth best path. Jump to the right, past the top edge of the screen. You will thus find a hidden path. Digging the sand beneath you, you'll come to a spot where there are three 1-Ups! Then collect the arches and enter the zipper to return to the main level. You will find yourself at the beginning of the level. Cross it again, as you did before, until you reach the finish line.

The first card you found is for CosMc's Retreat and the second is a secret card!