Revealing mistake: When Henry Hummle is transferring from the start of the long distance race to the gymnastics. he starts to "fuzz away" before the scene changes. (00:04:15)
Deliberate mistake: The 100-meter 'dash' goes over a longer distance and lasts longer than shown in the movie.
Other mistake: When Kit Mambo prepares to catch up with Renè Fromage, she first overtakes two guys (the raccoon and the bighorn sheep) on 'third and fourth positions' - as announced by Barbara Warbler, then she passes the sheep and the camel before she catches up with Renè. This would place her first competitors on positions five and four, instead of three and four.
Continuity mistake: When Boris Amphibiensky fails his high jump attempt during track and field, one of the bar's ends sticks to the post while the other reaches down to the ground. But the bar's length is only about an eighth of the posts' height, which is more than 77 feet, so the one end shouldn't reach the ground while the other still hangs on to the post's top.
Deliberate mistake: When Kurt Wuffner makes his downhill run, he temporarily slides down a vertical and then inward-going slope. I know it was made for humor, but at these extreme angles, neither trees nor snow could latch onto the surface in the first place.
Revealing mistake: When Bolt Jenkins lands right into the Gekko Flakes commercial, the whole scene shifts for a bit. Obviously, the cells got a bit messed up during layering while making the scene.
Other mistake: When Henry Hubble gets his massage and sauna treatment, he gets pounded on by the rhino and comments his work. But when he's saying the lines, he is not seen moving his mouth (or his upper head, for that matter, since his lower jaw is resting on the table).
Continuity mistake: When the boxer Janos Brushteckel sits in his dressing room after his crushing defeat, look at his right horn. In the opening scene it is broken; when Lodge Turkell urges him to watch the replay, it is whole; and later on it is broken again.
