When Koopa and his kids run past the suit of armor that Mario, Luigi, Toad, and the Princess hide behind, Hop's hair is pink instead of rainbow as he passes by.
The Koopa kids are assigned the task to dispose of all the trash. In the first shot of the kids arriving, Hop's hair is yellow. In another shot, his hair is blue. Then in the next shot, Hop and Big Mouth's heads are brown then change to their normal colors when they move. Also, Hop's eyes are blue.
Bully relaxes on the hammock and tells his siblings to get to work. In the next shot when Big Mouth protests, Hop's hair is yellow.
The trash returns to Dark Land and lands on Koopa. When he states it's not "neat stuff," his mouth changes from dark green to lighter green up until he orders Bully to make sure it doesn't come back.