When trying to escape from the STENCH HQ, the agents go through some large circular saws and Charles Hawtrey's suit trousers and jacket are both ripped. Yet, in the next part of the sequence, just before they go through the jets of water, he turns around and his suit is undamaged.
When Desmond Simpkins and Charlie Bind lure the doorman from the fun house, Simpkins hits him with a copper pot, and his fez falls off and lands in the middle of the doorway. In the next shot, from inside the building, the fez is nowhere to be seen.
Inside STENCH's HQ, the four British spies are on a long metal cylinder which is cut into four pieces with a spy on each piece. In the next scene, the cylinder is now in halves with the spies in pairs on each half.
When they are trying to escape the S.T.E.N.C.H HQ, Kenneth Williams drops one of the two spools of tape. The scene cuts away for a few seconds and when it shows them again, all of the tape has been collected up and both spools are back in his hands.
When Crump points out the cherries in their champagne cocktails at the Café Mozart, his and Daphne's cherry sticks vary in position between shots.
When Daphne recites part of the formula, she says it must be kept at -300 degrees Centigrade. This is of course impossible. Nothing can be colder than absolute Zero which is -273.15 degrees Centrigrade.
British Army sentries at the entrance to the secret research institute are armed with MP40 sub-machine guns - used by the German Army in World War Two. For the time of the film's production they should have had, either the L1A1 self loading rifle or the L2A1 Sterling sub-machine gun (although it would have been more forgivable if they had used the forerunners to these, the SMLE bolt action rifle and Sten machine-gun as opposed to WW2 German weapons).
@ around 1 hour 19 mins when the 2 guards shoot each other and fall to the floor one of the guards can be seen moving his hand slightly while he is laying on the floor.
Though it's all played for comedic purposes, when Dr. Crow (as being held by Lila at gunpoint) rewinds factory machine tape, it rewinds time itself (of the heroes going through the factory mechanism as shown on the monitor), when it would only reverse the mechanism of the machines.
In one scene, a pistol's bullet goes upward (breaking a chandelier down), due to the gun having a upward-bent barrel. However, in reality, a bullet would explode in the gun if it immediately hit the side of the bent gun barrel itself. This gig is played for comedic purposes.
When Charlie Bind picks up the formula in the Street of a Thousand Artisans, it is clear that the cobbled street upon which it has fallen is made of rubber. The cobble bends with the pressure of Bind's hand.
Kenneth Williams breaks the door's glass window when exiting the office. However there is no sound of broken glass when Richard Wattis or the foreign man who hands a message to Eric Barker when they the walk away from the door.
When Simkins closes the chief's door a sound of smashed glass can be heard; however if you look at the panes in the door you can see that they are not glass panes.