The name "Momo" was mentioned once in the whole film, by Aang at the Spirit Oasis. Momo was not shown named on-screen.
A mistake in the film occurred when Aang's hands supposedly touched and petted Momo after the lemur jumps on his shoulder. Aang's hands do not seem to actually touch the creature and instead, seem to hover about an inch or so above him.
In the film, Momo's tail has several stripes, contrary to the Momo in the series whose tail only had two stripes.
The wings Momo has in the film are orange, while in the series they were white.
Momo's appearance in the film, except for his ears and tail, is similar to that of a real-world lemur species known as the Coquerel's sifaka.
In the series, Momo's eyes were big and green while in the film they are smaller and yellow.
In the movie, Momo is only seen six times, (the best look at him was in the Southern Air Temple,) whereas Momo appeared multiple times in the series.