To get the Worm Doodle, Freddi cuts the hook off the fishing line and it falls, taking the Worm Doodle with it. When Luther catches it, the hook is gone (Luther catches just the Worm Doodle).
Freddi and Luther have four classmates (the gold fish with blue fins, the green fish, the blue fish, and the seahorse who said he saw the ghost). When they catch the ghost, five toys fall out of the bag. If Freddi didn't bring a toy, and no one brought in more than one toy (bringing in more than one for show and tell would be hard), this wouldn't be possible.
Casey appears to be the same age as Freddi and Luther. Considering that Freddi and Luther are supposed to be in school for the entire game, why isn't he in school as well?