Continuity mistake: When the dentist wants to put Nemo in a bag, it's a resealable one with a seam at the top. When he finally catches him, it has changed to a normal plastic bag.
Continuity mistake: Before Nemo is initiated into the Tank Gang, Brother Bloat introduces the Ring of Fire. Bloat then retreats and goes between the on-looking fish. In the next shot Bloat is on the outside/right. In the following shot Bloat is again in the middle. (00:38:15)
Continuity mistake: In the sequence with the boat, its position changes. When Nemo is looking at it with his friends, it is a long way away. When Nemo gets angry and swims to it, it's suddenly very near the reef. Then, the diver catches him when he's only been swimming away from the boat a few seconds, but the diver has to swim a long way back to the boat. Finally, when Marlin follows the boat, it's very near again, because he gets there before it starts, even though he was temporarily blinded by the camera. The boat does all this without raising the anchor until it leaves.
Continuity mistake: The "'For a bite that counts', alligator floss'" poster on the wall moves further from the window as Phillip Sherman grabs Nigel, then it suddenly moves back to its original position. The poster is first visible close to the window in an earlier shot. (01:19:50)
Continuity mistake: Towards the middle of the movie, we see a shot with Nemo staring out of the tank, depressed. The camera slowly pans toward the side of the tank and Nemo is reflected in the glass twice. However, towards the end of the movie when Nemo is playing dead, all the fish swim to the other side of the tank and Bloat says something like, "What's happening? Why is he playing dead?" The camera pans to the side of the tank again, but the fish are only reflected once this time. They should have been reflected twice.
Continuity mistake: As the fishing net is being pulled up, a fisherman is shown to the left of two wires on the boat leaning on his elbow. Then in the very next shot, the fisherman is in between the two wires, and now he is leaning on his hand.
Suggested correction: He isn't between the wires.
Continuity mistake: At the beginning of the film, Marlin sees that only one egg is left and he turns it over in his fins. In the other shots his fins are nowhere near long enough to do this.
Continuity mistake: When Marlin and Coral check on the eggs in the nest, when they first look, no eggs can be seen at the mouth of the cave but a couple of shots later the eggs appear.
Suggested correction: The reason the eggs appear is that the camera may have moved downwards, thus closer to the eggs that would have been at the bottom of the hollow. If it was more upwards, as in the first shot, the eggs would have been below the camera's view.
Continuity mistake: Near the end, when Marlin gets the fishing net off Nemo and talks to him a little about sea turtles, the rocks and seaweed nearby change between shots.
Continuity mistake: After Dory and Marlin passed the jellyfish and Marlin passes out, when the movie returns to the tank, the camera pans over the tank from right to left, and there's a reflection of the Sydney skyline. However, neither walls nor window frames show in this reflection. (00:45:55)
Continuity mistake: Jacques wakes up Nemo sleeping in his hut with a bunch of rocks. Nemo gets up and starts floating above the rocks. In the next shot, from the back of the hut, Nemo is still floating in the same spot, but the rocks have vanished.
Continuity mistake: Decorations inside the fish tank often disappear, appear in random places, or change directions and spots throughout the film.