When Carr Gomm first meets John Merrick, he walks close up to him. In the next shot he is way back from him, then close again.
When Dr. Treves is bringing up the oatmeal to John Merrick and Carr Gomm startles him, he puts the oatmeal behind his back as to hide it from him. In the next shot he has the oatmeal in front of him and puts it behind his back again while he is walking towards Carr Gomm.
When we see an image of smoking pipe stacks, it's obviously stock footage because it's much grainier than the rest of the film.
Bytes throws Merrick's mask out of the caravan. The mask then falls under the caravan's stair. But when Bytes' boy picks up Merrick's clothes, the mask is seen among the clothes.
In the film, Joseph Merrick befriends Dr. Treves before he is kidnapped and taken to Belgium. In real life, Merrick never met Dr. Frederick Treves until he was rescued by police from a train station in London as was shown in the film.
During Merrick's visit with Treves and his wife at their home, he shows them a picture of his mother. He expresses his desire to find her someday, but in reality his mother died when he was 11 years of age from bronchial pneumonia.
Joseph Merrick was far more independent than he is portrayed in the film.
Although it claims to be based on non-fictional writings and primary sources, the movie is full of historical inaccuracies and fictionalized incidents, starting with the fact that Merrick's first name was actually Joseph, not John.
Mr Carr Gonn the head of the hospital governors somehow knows John Merrick who frightened the nurse giving him breakfast is called 'The Elephant Man' but Frederick Treaves never told him that.
00:24:19 Frederick Treves says that Merrick is a complete imbecile probably from birth, then right after that says that he's a complete idiot. Imbecile and idiot were actually psychological terms, the former being someone with an IQ between 26 and 50 and the latter being those with an IQ between 0 and 25, so nobody could be both.