Director Peter Jackson makes his cameo appearance as the pierced punk, and then disappears between shots.
Frank's breakfast cereal changes from multi-colored Lucky Charms to bluish-purple Boo Berry between shots. Both boxes can be seen in the background.
After Frank crashes through Ray's fence, he deliberately backs out over a garden gnome, crushing its head. In the next shot, Ray is holding the intact head while screaming at Frank.
When Milton Dammers screams, "I'm wearing a lead breastplate!" and rips open his shirt, his tie is hanging nearly straight down. When we cut back to him, his tie is tossed over his shoulder, while both of his hands are still holding his shirt open.
During the scene in the museum the two guards fire at least 45 shots from their automatic pistols without reloading.
When Special Agent Dammers holds up his FBI ID, the shield badge on it is very unlike the FBI shield.
The swastika on FBI Agent Dammers' hand is reversed. It is first revealed in the car rear view mirror, where it looks correct.
When Frank goes to the Lynskey house he said it was 'spontaneous recurrent psychokinesis', but when he goes to another case he calls it 'recurrent spontaneous psychokinesis'. The fact that he can't keep his con man story straight makes the scene even funnier.
Bartlett refers to Ukrainian serial killer Andrei Chikatilo as "the Russian cannibal creep." Chikatilo's murder spree occurred when Ukraine was part of the Union of Soviet Socialist Republics, which Americans often referred to collectively as "Russian," so this is an acceptable misnomer for the period. Although Chikatilo was executed *after* the dissolution of the U.S.S.R., when Ukraine became an independent republic.
When Frank is having breakfast talking to his ghost buddies early in the film, the background clearly shows a sunset, not a sunrise.
When the eyes of Jeffrey Combs (Dammers) are shown in extreme close-ups, the edges of his contact lenses (which were probably used to make the actor's eyes darker) are clearly visible.
When Frank leaves the newspaper office, outside he sees Lucy being driven by in the limo. Then Ray runs right into him, while in the alley Ray calls Frank "Mike" when Frank is telling him about his new life as a dead man.
When Frank is at Ray and Lucy's house, he opens the refrigerator and freezer to squirt holy water inside. No light comes on when either door is opened.
Dammers refers to, "...the power invested in me..." The correct term is "vested", not "invested".
When Ray and Lucy are walking Frank out of their home, we hear the sound of Frank's toy gun being used when it is actually not. Also at that same moment we hear the sound of shoes on a hard floor when Ray and Lucy are wearing socks and walking on carpet.
When Ray hits the possessed doll with a pillow, the stand used to hold it up is clearly visible.
When the bed starts shaking with Lucy on it the lifting and shaking equipment under the bed is clearly visible.
(at around 1h 40 mins) When Frank and Lucy are hidden behind the shelf from Patricia, a wire can be spotted on the back of her dress, as she run past the screen to the left.
When Frank is recognized by the wealthy woman in the big house, the newspaper she holds, misspells "Psychic" as "Psycic."