When Mario and Luigi are finishing off the Sledge brothers after using super stars, they aren't flashing anymore. All you hear is the superstar music during the rest of the fight.
There's one shot where the spots on Toad's hat are gray instead of red when he has it off his head.
When Cheatsy is leaving the room after putting the wrestlers to sleep before Toad comes in, his head turns brown.
In one shot before Luigi flies across the ring to booby trap number one, the sledge brother's helmet is all white without any green.
In the shot just as Mario and Luigi grab Cheatsy and Koopa, Cheatsy's head turns brown in one of the frames before Luigi grabs him.
During the wrestling match, numerous shot cuts show that Cheatsy Koopa is seen both underneath the ring, operating the booby traps, and at the same time, he is also sitting in the bleachers, next to King Koopa.