Plot hole: In the pressure, Masami pretends Darwin is her boyfriend. However, in the storm, Masami is in love with Alan. So why didn't Masami just pretend Alan was her boyfriend?
The Mothers - S3-E17
Plot hole: When the "refrigerator" falls on Tobias's mom, the boys are watching from a side view. It is later revealed that the fridge was just a cardboard cutout. The boys were watching from the side, so how did they not notice it?
The Microwave/The Meddler - S1-E17
Continuity mistake: In "The Meddler", Nicole is feeding Gumball food with a spoon and drops it on the table. The camera cuts to Darwin and then back, but the spoon is now gone.
Continuity mistake: When Gumball enters the tent of sweaty cheese, he is covered in slime. When he comes out, he is clean.
Continuity mistake: When Gumball and Darwin board the bus, the bus driver pulls out an axe and the boys ask what it's for. The driver says he uses it to push the pedals and he is still holding it. In two shots, the axe has vanished.
Continuity mistake: Nicole arrives in front of The Pest control bug and steps out of the car. In the next shot, she is suddenly over the barrier, even though she did not previously step over anything.
Continuity mistake: The Kids are playing cards on the floor, with some cards in their hands and in a pile on the floor. Right before The Kids stop playing, the cards on the floor disappear.
Continuity mistake: Penny is looking next to the corner of a wall next to some lockers. In the next shot, she is now next to her locker, which is not that close to the corner she was just standing next to.
Continuity mistake: Gumball enters a bathroom where Banana Joe's father is taking a bath. At first there is nothing behind Banana Joe's father. In the next shot, two bottles of shampoo appear behind him. In the next shot, the bottles disappear again.
Audio problem: When Penny turns into a dragon, she begins to say something, but her speech goes faster than her mouth movements.
Continuity mistake: Penny sets up a ladder next to Gumball's window. The ladder disappears in the next shot, and reappears in a later shot.
Continuity mistake: Gumball pokes his tongue through a newspaper that Darwin was holding. In a few shots, the newspaper disappears.
The Allergy - S3-E16
Continuity mistake: The school nurse drops a pencil right next to herself. The pencil disappears in two shots.
Continuity mistake: A man breaks through the windshield of his car, spreading glass shards everywhere. In a few shots, The Man is still on the ground, but the glass shards have disappeared.
Continuity mistake: Gumball and Darwin are standing next to an open locker next to Tobias. The camera cuts to Tobias, and then back to the boys, but the locker is now closed.
Continuity mistake: Gumball and Darwin break through Mr. Robinson's fence, leaving some scattered pieces. In a few shots, the pieces are gone.
Other mistake: In "The Picnic", Darwin and Gumball bite into a rock. They each bite the rock with only two teeth each, but every one of their teeth cracks.
Continuity mistake: In "The Robot", There is a stuffed animal next to Darwin. In a few shots, the stuffed animal moves further away from Darwin by itself.
Continuity mistake: In "The Robot", Gumball and Darwin are playing with stuffed animals, which they set off to the side. Many shots later, the stuffed animals disappear.
Audio problem: In "The Robot", Gumball whimpers while his mouth is open. He whimpers again, and this whimper sounds like the first one, except his mouth is closed.
