Boom mic visible: Numerous, including reflected in a mirror.
Continuity: Jacob Singer walks from one subway car to another but when he exits the subway, the car is not there.
Continuity: To match the direction of movement, a shot of the Ford LTD racing around a corner has been flopped, but the license plate, which is now in reverse, is visible.
Anachronisms: The baseball cards that Jacob's son drops in the flashback of his death were Topps 1973 edition, after his death is supposed to have taken place.
Continuity: The amount of shaving cream on Jacob Singer as he talks on the phone. It appears and disappears during the scene.
Revealing mistakes: A support wire is clearly visible on one of the birds that are "flying" around during the party scene.
Continuity: Even through Jacob doesn't finish shaving (he towels-off the remaining shaving cream off his face), he appears to be clean and evenly shaven.
Errors made by characters (possibly deliberate errors by the filmmakers): Jacob's Doctor/guardian angel Louie shouts out for "Jacob Stinger" at one point when he is attempting to rescue Jacob from the hospital. Jacobs full name in the movie is Singer, not "Stinger".
Crew or equipment visible: When Jake puts his son to bed, there is someone visible in the mirror behind him when he leans down.
Anachronisms: In the house party scene, the song "Lady Marmalade" by Labelle is heard. However that song was first released in 1974, which is later than the period in which the film is set.
Errors in geography: The B train (that Jacob is riding) does not stop at Bergen Street and never did.