Visible crew/equipment: When Charles Hawtrey "jumps" onto the light near the end of the film you can see the strings pulling him across. The same can be seen with Jim Dale as well.
Continuity mistake: When Charles Hawtry is about to be beheaded, someone comes up to him saying they have a message for him. He replies with, "Toss it in the basket and I'll read it later." So she throws it in the basket, but in the next shot when you see an overhead view of Hawtry, the basket is empty.
Visible crew/equipment: When the guards are getting out of the carriage at the Bastille just after Camembert and Bidet have come back from England, you can see some crew reflected in the front of the carriage.
Continuity mistake: When Pomfritt is fighting the soldier at Chateau Neuf, the soldier is wearing a hat, but when the soldier smashes a bottle of wine with his sword in the next shot, the hat has disappeared.
Continuity mistake: When Pomfritt is fighting the soldier during the fight at Chateau Neuf, the soldier slashes the tapestry with his sword and cut marks appear. When we see the two fighting a little later on, the cut marks on the tapestry have disappeared.
Continuity mistake: When Malabonce is checking the guillotine, the position of his hands change from gripping the runners to by his sides between shots.
Revealing mistake: When Sir Rodney leaps from the banister onto the chandelier during the fight at Chateau Neuf, it is not Sid James but a stunt double.
Plot hole: Sir Rodney Ffing knows Jacqueline's name despite the fact that when the two of them first met, she never told him what her name was.
Continuity mistake: When Charles Hawtry is about to be guillotined, Sid James approaches to sell him insurance. While talking Sid places a snuff box on the blade runner just above the stock top. In the next shot the snuff box is much higher up the runner, causing the blade to stop well short of its victim. (00:13:05 - 00:13:55)
Revealing mistake: When the first fingernail drawing is attached to the guillotine with the knife, you can see the wire that was used to guide the knife attached to the end of it.
Audio problem: When Sir Rodney Ffing is disguised as Robespierre, his lips don't match what's being said. Plus when him, Darcy and Pommefrit are leaving, as he says "You two, come with me", his lips aren't moving at all.
