When Douglas Fairbanks swings down on the rope to meet Charlie, his foot is inside a loop at the end of the rope when he starts the swing in the wide shot, but when he lands in the tight shot, his foot is nowhere near the loop. Also the momentum created by the swing would have carried him much further than it actually did, i.e he wouldn't have stopped where Charlie was standing.
In one of the scenes Chaplin is playing tennis with Fairbanks, he switches from playing left- to right-handed.
When Minnie Chaplin punches out the cop during the escape sequence, she is seen wearing high heels. But when walking to the car in the next shot, she can be seen wearing brown boots.
When Mother is serving "fish head" soup to Charlie and his brother... She empties a ladle of broth into a bowl, then in a closer view is shown a fish head in the ladle which wasn't there a second ago.
At the Hollywood party, Douglas Fairbanks rope-swings from the balcony at about 30 feet in the air, yet in the next shot he comes gently to the floor at a speed and distance of only a few feet.
When Charlie is shown at the 1972 Oscars near the end of the movie, he is showed being brought to the podium in the wheelchair and then standing at the podium as the movie clips played. In the actual awards ceremony, Charlie walked out to the podium under his own power after the clips ended.
Although the end credits state Mabel Normand "never worked again", she made three features and then four shorts from 1923 to 1927.
When Charlie and Mildred Harris are in the bedroom, Charlie wants her to put lipstick on. She uses a metal tube twist up lipstick. The scene following this bedroom scene is dated as 1918. Twist up metal lipstick tubes were not invented until 1923 by James Bruce Mason Jr. in Nashville, Tennessee.
When Charlie Chaplin arrives in Hollywood in 1914, he interrupts the filming of The Adventurer (1917). However, that film was not made until three years later when he was already the most famous actor in the world.
During the scene where Chaplin demonstrates the power of silent films as Vaslav Nijinsky, he first gives him a high voice before correcting himself. Chaplin would've known very well what Nijinsky sounded like as he had met him numerous times in the 1920s and the two were good friends. (Source: The documentary "Chaplin Today" from the DVD release of City Lights)
While Chaplin is incorrectly depicted playing the violin right-handed (he was a left-handed musician), Chaplin wrote with his right hand.
When Charlie and his brother visit Fred Karno for Charlie's "interview", the opening shot shows a river with still water and a paddle steamer moves from left to right. The boat is moving a good deal faster than the paddle wheel is moving suggesting another power source.
When Chaplin is leaving New York City to head back to England in 1952, the composite shot of the ship, the skyline, and the Statue of Liberty shows that the super-imposed graphic for the Statue is what actually moves in the shot, to give the illusion that the ship is what is actually moving.
Following Chaplin's 1921 trip to England, there's a scene with Charlie and his pal Doug Fairbanks (Kevin Kline) who refers to visit from "the FBI". In the 1920s what later became known as the FBI was simply called the Bureau of Investigation, an office of the Justice Department. The Bureau of Investigation was renamed "Federal Bureau of Investigation" in 1935.
Towards the end of the movie there is a shot of the New York waterfront with the French ocean liner SS Normandie in the foreground, the subtitle showed the year as 1952. The Normandie was seized by the US government in 1942 and as she was being converted to a troop ship, caught fire and capsized at her dock. She was sold for scrap four years later.
Douglas Fairbanks opens a beer with a twist cap. It was not invented until the 1960s.
A Western Electric 302 telephone appears in the 1930s. The phone was first produced in the 1940s.
During the scene after the paddle boat is tied to the dock, Sidney and the boat operator open bottles of beer with screw off caps, something not made until the late 1970s.
When Charlie's brother and others arrive to whisk Charlie and his unedited film away to Utah, the car screeches to a halt. However, the car is on a dirt track and therefore no screeching noise would actually be created.
When Downey Jr (Chaplin) holds a hand mirror for the actress who is running late you see a crew member in the reflection for a split second before she leaves the room.
Mary Pickford stood at 5 feet while Maria Pitillo, who plays her in the movie, is 5 feet 4 inches tall.