Factual error: While Bridger is watching the film of the Mafia boss following Beckerman he signals for the film to be stopped so he can look at the close up shot of the man. He is watching a 16mm film shown through a bog standard projector - stop a film like that for more than two seconds without closing down the projector shutter (this doesn't happen - if it did the screen would darken instantly) and it will melt and catch fire. This doesn't happen.
Continuity mistake: During the infamous scene where Barbara Windsor loses her bikini top, Hattie Jacques is shown several times, but her hat disappears in one shot, reappearing in the next, and so on.
Revealing mistake: When McCullough is discussing Prudy's oddities with the matronly lady out front of the mayor's house, it is obvious that the lady is standing on a dirt-covered concrete sidewalk.
Visible crew/equipment: When Woody Allen cuts out a piece of glass out of a shop window, the camera, dolly, some crew members and a crowd of spectators can be seen reflected in the glass.
Continuity mistake: Gladstone has a drink in Dr Nookey's office, but he doesn't pour it. It just appears in his hand.
Factual error: In the 19th Street Parade, it shows the Budweiser Clydesdales pulling their famous wagon. Even though this movie is set in 1897, Budweiser did not start using Clydesdales until April 1933 when the sons gave their father, August Busch Sr., the owner of Budweiser, a 6 team team of Clydesdales to celebrate the end of Prohibition.
Continuity mistake: When Frosty gets off the train because Karen gets sick, from the magician's view it appears the train is slowing down and is very close to Frosty, but when the shot goes back to the magician, the train appears to be going much faster and is much further away.
Continuity mistake: In the restaurant kitchen scene, Carol Sanders takes hold of the waiter's left hand. In the next shot, she is holding his right hand.
Continuity mistake: At the end of the town collapse, a sincerely drunk Ben dives head-on into a tub where a lady (in her underclothes?) is just enjoying a bath. Propelled by Ben's momentum the tub with both passengers slides down the slippery planks and splashes into the river, while Ben rearranges himself into a comfortable sitting position between shots. If I wasn't completely mistaken also the lady changes her outfit, since the embroidery is missing when they float along. (02:23:35)
Factual error: During the celebrations for the end of World War II, cars can be seen in the background that were made long after 1945. Also in this scene in the shot of Piccadilly Circus, the BMC {British Motor Corporation} rosette logo can be seen among the adverts. BMC wasn't formed until 1952.
Continuity mistake: When Charlie Brown is doing the dog food for Snoopy, the amount of food in Snoopy's dish changes between the kitchen and the dog house.
Continuity mistake: Professor Quigley shows his students a grocery list, and then demonstrates how a computer can be used to make a phone call to the grocer's and place the order by playing a recorded message. However, the grocery items named on the recording do not match the items on the list.
Revealing mistake: Captain Beckman is in the tower shooting at a small German plane that is attacking the castle. He is told to aim for the engine but when he does and shoots it down its not the engine that smokes, its both the wheels that are smoking from some very obvious smoke tubes attached to the fixed landing gear.
Continuity mistake: A hospital nurse hands a cup of water to Billy Bright, so he can take some medication. In the next scene, the cup is back on the nurse's tray and Billy picks it up himself.
Visible crew/equipment: When Neil and Brenda are in the row boat, the bulge of the mic transmitter is visible at Brenda's lower back. (00:43:45)