Boom mic visible: [top]: When Brian's mother is buying rocks to take to the stoning, swinging from side to side.
Crew or equipment visible: Camera shadow on Brian when he first is chased by people who think he's the messiah.
Revealing mistakes: You can see that Brian is hanging on a bar by his hands when he supposedly falls off the balcony and knocks the prophet into a large jar.
Crew or equipment visible: Man with suit and tie is seen walking in the background of the "Always Look on the Bright Side of Life" scene when the camera looks down the line of crosses.
Audio/visual unsynchronized: During the crucifixion scene at the end, the first line delivered by Otto (of the suicide squad) appears to have been over-dubbed and does not match the line spoken at the time of filming. This is because an earlier scene featuring Otto and the suicide squad was cut, and thus a different line was required to introduce them (spoken by Michael Palin).
Continuity: The number of Roman guards searching the PFJ headquarters changes as they enter and leave the house.
Revealing mistakes: When the crowd of people that follow Brian claim he is performing miracles a blind man says he is healed. When he falls into the hole you can see there is a stunt mat there to break his fall.
Revealing mistakes: During the crucifixion scene, after the PFJ sing "For he's a jolly good fellow", you can see a very obvious double for John Cleese playing "Reg" amongst the PFJ when John Cleese enters the scene as the Centurion, looking to free Brian.
Continuity: The crosses being carried by the prisoners are considerably smaller than the ones they end up being crucified upon.
Crew or equipment visible: In the scene where the three wise men are praising Brian, an electrical extension lead is clearly visible hanging down on the right of the screen (wide screen format).
Anachronisms: In the scene where a nude Brian speaks with his followers and his mother comes storming into the room, a Star of David is visible on the wall of the room. The Star of David didn't become a symbol of Judaism until the Middle Ages.
Revealing mistakes: In the manger scene at the start of the film, John Cleese's Wise Man's make-up has clearly not been applied to his neck, and there are obvious lines on his face where the make-up has run from sweat.
Crew or equipment visible: As Brian is dragged away by Roman guards after the failed plot to abduct Pilate's wife, it's quite easy to see the padding in his costume that's there to protect him from the floor he's being dragged over.
Revealing mistakes: Brian is a first-century Jew, yet in the nude scene he appears not to be circumcised.
Errors made by characters (possibly deliberate errors by the filmmakers): In the scene where the centurion is correcting Brian's slogan (from 'Romanes Eunt Domus' to 'Romani Ite Domum'), 'Domum' is incorrectly referred to as the locative case (which would be 'Domi'), when it is really the accusative of place (which drops the preposition 'Ad' from 'Ad Domum'). The sentence 'Romani Ite Domum' is correct, however.