The character Chernobog, the demon in the sequence "A Night on Bald Mountain", switches from no nipples on his chest to having nipples numerous times.
When the Pegasus foals are jumping in the water, the blue one jumps in, becomes the orange one, then the blue one surfaces and the black one, who is shown diving afterwards, and the pink one is suddenly in the water.
In the "Sorcerer's Apprentice" sequence, as Mickey Mouse
waves his hands in front of him to make the broom come to life, his sleeves spill over his hands. It then cuts to his shadow on the wall, where his hands are fully exposed.
Two of the dancing mushrooms in the "Nutcracker Suite" inexplicably change size and shape (from wide and medium height to skinny and tall) when the angle changes.
The dancing ostriches in "Dance of the Hours" are portrayed as females, but it is only the male ostrich that is black and white. The females are gray-brown.
In the third section of the "Pastoral Symphony", the character known as Bacchus is misnamed. Bacchus and the Greek equivalent Dionysius are always depicted as young men. The fat, drunken man corresponds to Silenus, the teacher and companion of Bacchus. Silenus is always depicted in much the same way as the character in the movie. The two are often confused.
The Pastoral sequence has Iris sweeping across the sky after the storm, leaving a rainbow in her wake. The colors of the rainbow are reversed: Red should be at the top and violet at the bottom.
In the Sorcerer's Apprentice sequence, as Mickey walks toward a stone wall his shadow slowly grows larger. Instead, it should grow smaller. However, this could be excused as artistic licence to make the scene more dramatic.
During the "Pastoral" segment, when the first centaur and centaurette walk away together arm-in-arm, a bush in the lower right fails to track properly, and winds up going with the pair.
The creatures gathered at the dinosaur water hole include animals exclusive to different time periods. Stegosaurs lived only in the Jurassic Period, Ceratopsians only in the Cretaceous, and Dimetrodons only in the Permian. It is possible that this was not yet known in 1940.
During the night in bald mountain sequence any one walking the streets at night would have seen what was going on .
In the full-length introduction to the "Nutcracker Suite", heard only in the roadshow version of "Fantasia", Deems Taylor states that this music is from a longer ballet called "The Nutcracker" and "nobody performs it nowadays". The full-length "Nutcracker" had not been performed in the U.S. yet in 1940, but in both Russia and England it had been staged in 1934, and had already been staged in Russia twice before that, in 1892 and 1919. However, although the "Nutcracker Suite" was immensely popular even in 1940, the full-length ballet was still a long way off from becoming the annual phenomenon it now is in the United States.
When introducing the "Pastoral" sequence, Deems Taylor mixes Greek and Roman names of deities: Bacchus, Vulcan and Diana are Roman; Zeus, Iris and Morpheus are Greek. Apollo is the only one whose Greek and Roman equivalents have the same name.