When Deuce is being beaten up Claire, her shoes disappear for one shot. It happens just after he is kicked in the face three times to the music beat (still on at that time). When she does the spinning round kick she has no shoes on. After this kick they are back on again. It's only at the end of that scene that she takes them off asking Deuce not to tell Antoine about them.
When T.J. and Deuce are going through and looking at each one of the fish in the miscellaneous containers, they come across one fish lying on the bottom, which has a toy scuba diver sitting near it. The scuba diver changes positions in relation to the fish several times between shots.
At the fish store, Alison gets her entire chest wet, logo and all, while bending over to get something out of the tank for Deuce. In the next scene everything is dry except the immediate area around her breasts.
Near the end when Deuce Bigalow asks Allison (Fish Shop Clerk) for sea snails, she is wearing a flowered skirt, but when she goes to get the sea snails out of the tank, she's wearing the black jeans from the first scene.
Right after Deuce gets fired from the aquarium and ejected from the premises, he carries his equipment including a bucket away from the onlookers. There is no water leaking and the footpath is dry where he has walked. In the next scene, as Deuce gets off the bus, water is pouring from holes in the bottom of the bucket and causes a female passenger to slip over.
After Kate finds out Deuce was paid to originally date her, he is plunging a toilet for the second time apparently searching for a flushed fish. He plunges and a piece of excrement flies into the bowl. When he hands the bowl to the child, the plunged substance is missing from the fish bowl.
After Deuce and Kate leave the sushi restaurant, they walk to the end of the pier and he frees the fish that was going to be his meal. When he dumps the fish out of the bag into the "ocean," the splash is way too high and way too soon to have been the ocean below. The fish was dumped into a bucket or something held just below the camera line. Rob Schneider laughs visibly after this because the splash nearly hits him.