Continuity mistake: Vera gets onto her bus just after Stan and Jack have put spiders in the cab. She is wearing boots when she discovers the spiders, causing her to run into the back of the lorry. As she does so, it is evident that she is wearing shoes.
Continuity mistake: Polly Browne is in her dressing room with a picture of Tony Brockhurst on her mirror. She starts to sing and picks the picture off the mirror. As we see a close-up in her hands it is a totally different picture of Tony. As she puts it back, the photo has reverted back to the original.
Revealing mistake: When the bats invade Dr. Dunwoody's bedroom, you can see the strings on one of them.
Revealing mistake: When the platoon hear the church bells, they mistake it for the invasion signal and construct a barricade across the high street. If you look behind them you can see cars parked on the road in the distance that date from well after the 1940s.
Continuity mistake: When Gran first dangles down from the ventilation shaft, the slaver's key ring is too wide to fit through the opening. But when Jim loses his balance and Gran is jerked back into the cell, the key ring is suddenly much smaller than before.
Factual error: When Lurcio is dragging his ass through the market he passes several stalls which stock fruits and vegetables totally unknown to the Romans - potatoes, corn, papayas, mangoes and breadfruit amongst them. They were unknown in Europe during the time the film is set, and the Romans did not trade with anyone who knew about them, either.
Other mistake: When the Mayflower truck is on the move picking everyone up for the heist, a mysterious hole appears above the truck's cab, cut out in the letter "o" in "Mayflower" when Pop is picked up, that wasn't there a moment before, and then it vanishes. The same thing occurs after the heist, when the truck crashes into the police cars.Super Grover
Continuity mistake: When the farmer threatens Henry VIII with a fork after he catches him in the barn with his daughter, you can see that Henry is holding on the fork and it is well away from his body, but in the next shot the fork is pointing near Henry's face.