Errors in geography: The story takes place in New York, however, visible through the office window in one scene is the Westin Bonaventure Hotel in downtown Los Angeles.
Continuity: Prot removes his glasses and lays them down so that the top of the glasses are laying on the table. Later, when Mark Powell rushes in, the glasses are lying right-side-up.
Continuity: The first time we see Mark Powell's daughter she says that she lost her front tooth. The next time we see her she smiles and still has her baby front teeth.
Crew or equipment visible: When the doctors are meeting the film crew is reflected in the shiny silver coffee pot as one of the doctors pours coffee.
Errors in geography: In the opening scene Prot is arrested in Grand Central Station. In the next scene when the cops are escorting him to their van, they are walking along Park Avenue towards (not away from) Grand Central Station.
Continuity: Early in the movie, Mark leaves the city on the train at the end of the day in overcast weather, but when he gets home at 6:30, it's bright daylight outside.
Continuity: When Prot visits the doctor's home his sunglasses are alternate between plain and silvered between shots.
Factual errors: When Dr. Chakraborty is talking about Prot's vision, he describes him being able to see ultraviolet at 300-400 angstroms. Generally in the context of vision, ultraviolet wavelength is ~280-400 nanometers or only 2800-4000 angstroms.
Continuity: When Mark Powell runs off the train when he sees "505" on Prot's pencil, he is not carrying a bag. However, when he is at the telephone booth he is carrying a bag.
Continuity: Every time Dr. Powell commutes home, a MTA NYCT A-Division (IRT) subway train is shown traveling on an elevated structure. The interior of the train, however, is an MTA commuter rail train (which is more likely to travel to the type of neighborhood he is shown living in).
Errors in geography: At 1:29 in the movie, when Dr. Powell drives from the airport to Guelph, which is supposed to be in New Mexico, it shows him viewing the Park City arches at Arches National Park in Moab, Utah.