Six cast members played 40 characters.

In the interview section of Monty Python's Flying Circus: Live at Aspen (1998), John Cleese said that because of the massive protests against this movie from all denominations of Christianity, he would joke with Michael Palin, "We've brought them all together for the first time in 2000 years!"

To receive a "AA" certificate in the UK, allowing audience members under 18, the word "cunt" had to be removed from the scene where Reg blames Brian for allowing the Romans to almost discover the resistance's secret hideout. "Klutz" was overdubbed, though it's quite obvious to the audience what John Cleese is saying.

When Michael Palin as Pontius Pilate addressed the soldiers daring them to laugh, he was truly daring them. The soldier extras were ordered to stand there and not laugh, but not told what Palin was going to do. Palin, in fact, can barely stifle his own laughter when saying "Biggus Dickus" in front of the soldier asked if he finds the name "risible."

After the first take of the scene where a nude Brian addresses the crowd from his window, actor/writer/director Terry Jones pulled Graham Chapman aside and said, "I think we can see that you're not Jewish," referring to Chapman being uncircumcised. It was corrected in subsequent takes with a rubber band.

Continuity

The number of Roman guards searching the PFJ headquarters changes as they enter and leave the house.

When the Gladiator has a heart attack in front of the entrance gate to the arena. A high ranked Roman then makes the comment absolutely dreadful. Next scene the gladiator is no longer in front of the entrance gate. Note, the gladiator who suffers the heart attack was called a Hoplomachus gladiator.



Factual errors

A Roman centurion in full dress would be recognizable by 3 things: greaves covering his shins and knees, a vine in his hand and especially a helmet with the crest positioned from left to right. John Cleese's centurion is wearing none of these badges of rank. His helmet is in fact more like that of a Roman general.



Revealing mistakes

During the crucifixion scene, after the PFJ sings "For He's a Jolly Good Fellow", a very obvious double for John Cleese is playing "Reg" among the PFJ when Cleese enters the scene as the Centurion, looking to free Brian.

The prisoners carry crosses considerably smaller than the ones they end up being crucified upon.

At the place of crucifixion there are a number of 'empty' crosses already there with some corpses even shown being cut down. However, every prisoner brings their own cross to which each is tied one by one before it is erected, and later shots show that all the crosses on the hill are eventually used. If the Romans reuse the crosses then there is no reason for (at least some of), the prisoners to carry their own. Plus if, as stated, there are hundreds of crucifixions a day there should be many more existing crosses in place.

In the manger scene, John Cleese has obvious lines on his face where his make-up has run from sweat.

When Brian falls off the balcony and knocks the prophet into a large jar, he is clearly hanging on a bar with his hands.



Anachronisms

The letter U first appeared around the 14th century. At the time of Jesus, ROMANES EUNT DOMUS would be written ROMANES EVNT DOMVS.

When a nude Brian speaks with his followers and his mother storms into the room, a Star of David is on the wall. The Star of David became a symbol of Judaism in the Middle Ages.

When Brian is haggling with the merchant, they're referring to Shekels as currency, but when the merchant states a price, he follows with "and not a penny more".



Audio/visual unsynchronized

When the Suicide Squad arrives during the crucifixion scene, Otto's first line is clearly dubbed. An earlier scene featuring the Suicide Squad was cut, so Michael Palin needed a different line to introduce them.



Crew or equipment visible

During "Always Look on the Bright Side of Life," when the camera looks down the line of crosses, a man in a suit and tie walks in the background.

When the three wise men praise Brian, an electrical extension cord is clearly visible, hanging down on the right of the screen (widescreen).

Around the 43 minute mark you can briefly see one of the crew underneath the alien puppets (the one on the right) when both aliens jump up as the ship comes under attack.

A camera shadow appears on Brian the first time people chase him, thinking he's the messiah.

After Brian had his speech and the people pursue him asking him to complete his sentence, there is a frontal shot where the cameraman's shadow is visible on the crowd and Brian.



Errors in geography

Pontius Pilate is portrayed as having a palace in Jerusalem. Although one would easily assume this, due to his role in the New Testament, he actually resided in Caesarea, which was the Roman capital of the Judean province. There are historical mentions of Pilate visiting Jerusalem, but he never lived there.

Whilst selling concessions in the arena, Brian offers jaguar and ocelot bits. These are New World animals not to be discovered for 1500 years.

According to the caption text, Brian meets the People's Front of Judea for the first time in the Colosseum in Jerusalem. In fact, the only amphitheater known as the Colosseum is the big one in Rome, officially called the Amfitheatrum Flavium.



Plot holes

When Brian is picked up by the alien ship after falling off the tower, there is no explanation how he actually got into the ship, he is just inside the cockpit behind the two aliens. There is no decompression, and the ship is not damaged either, so it must be assumed that he fell through an open airlock on the top of the ship. They even fly into space and back to earth, so it apparently closed after he was inside the ship.

Jesus speaks in 16th-17th century English but everyone else speaks in modern English.



Boom mic visible

When Brian's mother buys rocks for the stoning, the boom mic is visible at the top of the screen, swinging from side to side.

When the priest starts reading out the name of the person to be stoned, the shadow of a boom mic is visible on the wall behind him.



Character error

When the Centurion corrects Brian's slogan, "Romanes Eunt Domus", he says Domum is the locative case, which would be Domi. It's actually the accusative of place, which drops the preposition Ad from Ad Domum. However, the resulting sentence, "Romani Ite Domum", is correct.