In the very first scene, when the woman is shot, her shirt is covered in blood. When she is shot again, even more blood stains her shirt, but when she falls back, her shirt is completely free of blood.
When Deborah removes her theatrical make-up, her hands get covered a mix of greasepaint and make-up remover. When she says "I thought you might know why"- "Me? Why me?" they're clean.
When Fat Moe gives Noodles the locker key, he opens the door of the clock. The key for winding up the clock is in place. After a quick cut to Noodles, the key is gone.
When Noodles stabs Bugsy they are on the left side of the Manhattan bridge. But when the police are coming, the whole scene is moved to the right side of the bridge.
When Noodles is visiting Deborah, during the various cuts when she is telling him to take the back door out, the makeup is almost gone. When she is standing by the door the make up is back in places. Also through the conversation the make up disappears and shows up in places.
Chief Aiello wears Captains insignia, not police chief's rank.
When the cargo floats to the surface in the scene in the harbor, the crates are floating with the balloons out and on top of the water, offering no extra buoyancy, and therefore not needed. This was because the crates did not contain glass bottles, which would have kept the crates submerged.
In the credits, the song Yesterday is "Used by permission Norther Songs Ltd." where it should say "Northern Songs Ltd." (including the second 'n' in Northern).
Darlanne Fluegel's last name is misspelled in the opening credits.
In 1968, Noodles rents a 1962 Pontiac, which is far too old to be in a rental fleet.
When Deborah is a child her eyes are green; when she is an adult they are blue.
When Max and Noodles are on the beach, Noodles' girlfriend lays a newspaper across his face. When the wind blows, you can see duplicate pages, revealing that it's a fake newspaper.
When Noodles talks to Deborah in the dressing room after her play, every time she raises her voice it reverberates like she'd be talking in a big hall - which is because the small dressing room is a set, presumably with one wall and the ceiling missing, built on a big sound stage.
The film is supposedly about Jewish gangsters. But the director is a noted Italian, all of the gang members are distinctly Italian actors, many of whom are famous for playing Italian gangsters, and there isn't a Jewish or Yiddish accent to be found among them.
It's the late 60s and Noodles sees the young man (David) born of "Mr Bailey" and Deborah's relationship. His age is not mentioned but he looks 20 max. That meant he would have born in the late 1940s, maybe early 1950s. Deborah is first shown in the mid 1920s and she's well into her teens. She would thus have been in her late 40s when David was conceived--not likely.
In November, 1968, when Noodles visits the locker in the station and pulls out a wad of US Currency, the top bill is signed by W. Michael Blumenthal, President Carter's Secretary of the Treasury from January 23, 1977, to August 4, 1979.
Just before the boys demonstrate the salt trick to the Italians, fluorescent lighting is visible inside the large buildings in the background. Fluorescent lights weren't commercially available until the 1940's.
In 1968, Noodles returns to the train station and opens a briefcase full of money. As he gets set to close the briefcase, we hear the chug-chug of a steam locomotive starting up in the background, then a steam whistle sounds. The New York state assembly banned steam locomotives from New York City in 1923 with the Kaufman Act. In the US, most steam engines were replaced with diesel locomotives by 1958.
While Dominic looks at himself in the mirror, just after the boys talk about the deadbeat newsstand vendor, a lady can be seen behind him picking up a 50-star U.S. flag. But the flag in 1920 had 48 stars.
In the scene at Miami Beach which takes place in 1933, beach goers are seen playing with beach balls. The beach ball was not invented until 1938.
When Young Noodles holds Young Peggy in the toilet and she says "You better stop squeezing me, or I'm gonna poop in my pants", the beginning of her line sounds twice, as if two different takes have been overlapped with a cross-fade.
The scenes at the Miami hotel show the sun setting over the water. Miami is on the Atlantic coast, so the sun should set over land. The scene was shot at St. Petersburg beach, on the Gulf coast.
When Deborah's train leaves for Hollywood, a French railroad car (SNCF) is on a track in the background. Above the French car, a sign can be seen saying "Voie 13", which is French for Track 13, indicating this scene was shot at a French railway station.
When Noodles and Max confront for the first time, while unloading the chandelier and Noodles takes the watch back, the police officer asks where he got the watch, who gave it to him. They respond that it was from Noodle's little brother, Max's uncle, who was from Chisinau Poland.
In 1920, Chisinau was a city in Romania, later being capital city of the Republic of Moldova, it was never part of Poland.
The boys first put money in a locker at the Lackawana Terminal in Hoboken, NJ. When they come out into the street, they are at the base of the Manhattan Bridge in Dumbo, Brooklyn, some distance away.
When the boys are in the train station, an announcement is made for the Lackawanna railroad train to Poughkeepsie and Albany. The Lackawanna did not run to these cities it was the New York Central Railroad.
In 1921 after the boys conceive and complete the job of smuggling liquor in through the harbor, they now have a huge amount of money in payment from rum runners that they keep in a brown leather case. They put the case in a safety box at the train station and later give the key to Fat Moe, who may or may not know whats in the case. The key can only be retrieved from Moe when all the gang is together. As the film moves through the years to 1933 then to 1968, several of the gang have been killed. After Max, Cockeye and Patsy are supposedly killed in the 1933 ambush, Noodles goes to the safety box to look for the money -- its not there. He spends 35 years in Buffalo trying to figure out what happened to it. In 1968 he is tracked down by Max, (who has the key and money and who was supposed to be dead), and goes to the safety box and finds the money in the same leather case.
The issue with the key is that Fat Moe had it and after the deception of the 1933 murders Max could only have gotten it from Fat Moe. Noodles goes and checks for the money meaning he had to have gotten the key from Fat Moe but the money was already gone. Noodles later did suspect Moe of taking the money but found Moe living in poverty in 1968 in the same shop. All in all why did Noodles wait 35 years to get the notion of asking Fat Moe if he had given the key to anyone? Moe would've HAD to have known Max hadn't died in order to give the key to him. Moe shouldn't have had any motive to take the case 'cause he was supposed to not know what was in it.
The issue with the key is that Fat Moe had it and after the deception of the 1933 murders Max could only have gotten it from Fat Moe. Noodles goes and checks for the money meaning he had to have gotten the key from Fat Moe but the money was already gone. Noodles later did suspect Moe of taking the money but found Moe living in poverty in 1968 in the same shop. All in all why did Noodles wait 35 years to get the notion of asking Fat Moe if he had given the key to anyone? Moe would've HAD to have known Max hadn't died in order to give the key to him. Moe shouldn't have had any motive to take the case 'cause he was supposed to not know what was in it.
When celebrating the end of the Prohibition Era, four bottles are opened with machetes. However, the actor in the back to the right fails to open his bottle cleanly and accidentally smashes it in half before quickly walking off-screen with the broken bottle.