When getting ready to see the neighbors, the boy's hands are on the same pane of glass in the window, but in the next cut, his hands are on different panes.
The hand the doctor holds the glass of water with changes between shots.
The chalkboard goes from wet to dry between shots.
In the US subtitles, the opening says that this is a true story that happened in 1978. It should have read 1798.
The dog that is killed by Victor at the beginning lifts its head just before it disappears from the frame and is seen breathing in the next shot.
Automobile traffic can be heard on the soundtrack during some of the scenes which take place in the Revolutionary France-era Institute for the Deaf.