Factual error: The gasolier, gas light fixture, in the entryway to Paula's aunt's mansion is the type/form that would have been used in a room, not in a hallway. The gasolier in the mansion bedroom used by Gregory Anton, Charles Boyer, is the type/form that would have been used in a hall and would not have been used in a bedroom.
Gaslight (1944)
1 factual error - chronological order
Directed by: George Cukor
Starring: Joseph Cotten, Ingrid Bergman, Charles Boyer, Dame May Whitty, May Whitty
Continuity mistake: When the maid is out on the street calling a cab, the policeman shows up. The distance between them changes from close to farther away, between shots.
Paula Alquist Anton: It isn't here, you must have dreamed you put it there. Are you suggesting that this is a knife I hold in my hand? Have you gone mad, my husband?
Trivia: Gaslight was teenage Angela Lansbury's first film and first Academy Award nomination and Ingrid Bergman's first Academy Award win.