Other mistake: Mrs. Petrie, Dr. Flemming's secretary, makes two phone calls to Joan Hudson. She dials seven numbers for the first call but only six numbers for the second call.
Columbo: Prescription Murder (1968)
1 other mistake - chronological order
Directed by: Richard Irving
Starring: Peter Falk, Gene Barry, William Windom, Katherine Justice
Revealing mistake: Just after the scene where the doctor asks Columbo to switch off the light before leaving, the detective does so, but it can be seen that both light switches are down before he does this, and that they are still both in the down position after he "switches off" the light.
Lt. Columbo: There must be something wrong with me. I seem to bother people, to make them nervous.
Trivia: The first choice for actors to play Colombo was Bing Crosby.