Continuity mistake: When Napoleon is feeding Tina, he stretches his arm over the fence and there is a rope visible. The rope repeatedly goes from being closer to further away from Napoleon's arm.
Continuity mistake: When Summer and Trisha are handing out "vote for Summer" fliers, in the close up of Summer handing them out you can see that one of the girls has on pink nail polish. Moments later, in a shot from a further distance (yet close enough to see nails), neither girl has on any pink nail polish.
Continuity mistake: When Uncle Rico is eating steak in the kitchen, the roll of paper towels changes before he takes one for a napkin.
Continuity mistake: When Uncle Rico hands Trisha and Summer the "Bust Must" fliers, at the end when they show a close up of them reading it, there are two sets of hands holding up the paper. However, in the shots both before and after, Trisha is only holding up the flier with her right hand.
Continuity mistake: When Napoleon, Grandma, and Kip are all in the kitchen area, in the shot of Grandma leaving, the container is nowhere close to the counter top edge and next to what looks like a phone book. Two shots later, in a close-up of Kip, the same food is now close to the counter top edge with the phone book nowhere to be seen. As the two argue in different shots, the container of food moves back and forth. On top of this, the phone book that was there in the original shot has mysteriously disappeared from every subsequent camera angle.
Continuity mistake: When Rico stops at the farmhouse while taking Napoleon to get his prom date, watch the passenger-side outside mirror on the van. While driving, it is positioned at a normal angle to see straight back from the driver's vantage point. When Rico gets out at the farmhouse, the mirror has been turned substantially and now sticks straight out.
Continuity mistake: Tina is not tied up to the fence, when Napolean first begins feeding her.
Continuity mistake: In the scene where Napoleon tells Uncle Rico to leave, Uncle Rico is throwing footballs in front of the video camera. There are three footballs; two on the ground and one in his hand, yet he throws four.
Continuity mistake: When Uncle Rico tells Napoleon about the sale in Bemida the jar/ glass of milk was not lifted up before the shot of Rico putting it down. It doesn't seem like he had picked up the jar before then because we can see it in Napoleon's shots.
Continuity mistake: When Napoleon calls Kip from school, you see that he was grating cheese for nachos. When the view goes to Napoleon and back, you see that the position of the block of cheese and amount of cheese on the chips changes. This happens multiple times throughout the scene.
Continuity mistake: During the opening scene on the school bus, they drive past a neighbor's barn as soon as they pull away from Napoleon's house. There was no gap in time because the dialogue is continuous, yet later when Napoleon walks out his front door to feed Tina, the closest neighbor in that direction is far off in the distance.
Continuity mistake: At the very end, when Napoleon asks Deb if she wants to play tetherball, the sprinkler system behind her disappears.
Continuity mistake: When Kipp places the bowl by the tire, the tire is to the left of the bowl with the curb behind it. When a full shot of the van is shown, the view is now opposite with the curb in front of the bowl, but the tire is still to the left.
Continuity mistake: When Napoleon throws the fruit on Uncle Rico's van, it hits the windshield and leaves only splatters of juice on the windshield, but when Rico stops the van, the windshield has several chunks of the fruit on it.
Continuity mistake: When the class president candidates present their program and perform some skit, there are several shots of students sitting in the auditorium. Keep your eye on Deb. She sits in the third row on the left side, but in the first and second shot she isn't there. Then she appears, disappears and finally reappears and changes her position by one seat.
Continuity mistake: When Napoleon arrives at Pedro's house just after he has cut his hair and is sitting on the lawn, his bike is upside-down with the reflector in the shot. When the camera comes back to Pedro, the bike reflector has moved out of the shot.
Continuity mistake: When Deb shoves the box of keychains into Napoleon's arm, between shots the green keychain on the far right disappears.
Continuity mistake: When Uncle Rico and Kip are eating at the restaurant, Uncle Rico's straw goes from straight up to the left and to the right.
Continuity mistake: When Napoleon asks the woman if he can use her phone, the position of the phone's cord changes between shots.
Continuity mistake: When Napoleon is waiting for Uncle Rico, he checks his watch and it says Thursday, July 17. This movie is set during the 2004-2005 school year, as seen on Napoleon's lunch card at the beginning. July 17 was on a Saturday in 2004 and on a Sunday in 2005, not Thursday.
Chosen answer: This is never explained or referenced.