During the scene (in 1980) where Nicky is changing cars multiple times to avoid the feds, a CAT (Citizens Area Transit) bus stop sign is visible. The Las Vegas bus system was not called CAT until 1992.
In the first newscast scene, before Ace's license hearing (which takes place around 1980), the Mirage hotel and casino can be seen in the background shot of Las Vegas. The Mirage was not completed until 1989.
in the scene where Ginger and Sam/Ace are at dinner at a restaurant, the camera keeps switching back and fourth to Ginger and Ace, when the camera is looking at Ginger, Ace is talking to her, but he is not moving his mouth.
When Nicky and Frank are being photographed by the feds outside the Gold Rush, one of the agents is using a camera with a motor drive sound effect. However, he is shown manually using the camera's film advance lever instead.
When Pat Webb is meeting with Ace to ask for Don Ward to be rehired as the slots manager, Ace responds that Webb's accusation is "libelous." For Webb's comment to have been "libelous," it would have had to appear in print. Ace should have said that Webb's accusation was "slanderous."
When Lester calls Ginger after her wedding, he says he always remembers her as a "long legged little colt". A colt is a younger-than-4-years MALE horse. He should have called her a "long legged little filly".
When Nicky and Sam are in the club talking a shot from the back shows Sam putting out his cigarette, in subsequent shots of Sam from the front the cigarette is lit, and when it returns to the back the cigarette is out.
After Nicky has stabbed the man with the pen in the bar, he puts the hand that was holding the pen up on the bar counter. Although, the pen that was in his hand had been covered in blood, his hand is clean.
When Ginger is smashing her car in to the back of Sam's car, she drives up the path towards the house and parks the car diagonally across the path. When we see the car next it is perfectly parked on the path.
When Piscano is ranting in the Italian Grocery about the trips to Vegas, the money his mother is counting appears and disappears between shots. He also knocks over bottles of olive oil which are reassembled in the next shot.
In the restaurant scene (Nikki's restaurant) where Ace confronts Ginger who is drunk, the wine/martini glass in the middle of the table is knocked over, then is upright again, then is over, then upright again.
After Ginger and the man next to her stop playing (at the 22nd minute of the movie), the man says "This $100 is for you, love. Thanks for your time". Then Ginger says "Come on" with a serious expression in her face. Immediately after, the angle of the camera changes while the man says "What's the matter?" and Ginger is laughing. Immediately after again, the camera returns to the first angle and then Ginger has a serious expression again.
When Nicky, Frank Marino, Jennifer are in the kitchen after they return home from their flight, Nicky makes Jennifer turn her head upside down to have the diamonds he stole & smuggled through airport security fall out of her hair up-do onto the table. After all they all fall out, her hair "bun" releases and is hanging down in an undone, long ponytail. But immediately after that shot when the camera switches angles, Nicky slaps her on the cheek and her hair is back up in a bun the way it was originally.
When Sam and Nicky are driving down the strip, and Nicky is having the conversation with Sam about what he thinks of him moving out to Vegas, the lengths that both of their windows are rolled down changes from shot to shot (especially Nicky's), and it's obvious that neither of them actually touch the window control to put it up or down.
SPOILER. As Nicky and his brother are being buried in the desert grave, Dominick is dumped into the grave first and lands on his right side, facing right. The next time we see him, moments later, he is lying on his left side, and facing left as Nicky is dumped on top of him.
When Nicky calls Sam after Sam kicked the big cowboy from Nicky's crew out of the casino for cursing him, Nicky apologizes, then hangs up the phone. Nicky then asks the cowboy why he "took off his boots and put his feet on the blackjack table." However, Sam never told Nicky this information.
When Ginger and the smarmy gambler finish playing the craps table, there are 3 very quick shots of him handing her chips. In the he first 2 shots, he is holding 2 chips, but in the third shot, he has 4 chips in his hand.
During the opening montage, Piscano's mother is preparing a meal in the back of the grocery store and is wearing a noticeable cast on her left hand. Later in the film, while Piscano is ranting to his brother-in-law about his bosses, she can be seen again, still wearing the same cast but the two scenes take place nearly a decade apart.
When Nicky is playing blackjack in the Tangiers and getting very hostile with the male dealer, Nicky throws a card back at the dealer and it gets stuck on his shirt. The dealer looks over to the pit boss with the card still stuck to his shirt, but in the next shot, the card is gone.
When Ace and Nicky are supposedly driving in Downtown Las Vegas, the view differs from each of their side windows. The Fremont Hotel is visible out of one window, and the Sahara out of the other. The Fremont is on Fremont Street, while the Sahara is on the Las Vegas Strip.
When Nicky first comes to town, Ace shows him the panoramic daytime view from his corner suite. The only high rise building that can be seen is the Landmark (demolished). Later, in the scene where Ace proposes to Ginger, the same view, at nighttime, is instead filled with high rise buildings as well as nearby Dunes and Frontier marquees. The nighttime view is clearly fabricated; the south-Strip Dunes (demolished) is nowhere near the north-Strip Frontier (demolished). The daytime view implies the corner suite is somewhere inside the Las Vegas Hilton.
The film takes place in the (fictional) Tangiers casino, but in one of the scenes in Robert De Niro's character's office, you can clearly see a calendar for the Riviera (the movie was primarily filmed in the Riviera.)
Although this is refuted, the scene where Nicky murders witness Anna Scott should be considered an error. His arm is on the other side of her skull in the line of fire. How a professional assassin would KNOW that the bullets wouldn't exit into his arm is ludicrous. No experienced killer would take the chance. The writer says they were likely short bullets, but there is no basis for that conclusion.
When Nicky shoots the lady in the kitchen his arm is placed directly in the gun's aim and is not hit by an exiting slug. However, since the bullets were .22 caliber, and quite likely shorts, they likely never exited the skull.
Don Ward, the fired overseer of the slot machines, is said to be the county commissioner's cousin, but later is said to be a brother-in-law. These terms are not mutually exclusive - his "hillbilly" accent makes it even easier to believe that he can be both.
During kitchen scene in Leaning Tower restaurant near end of film, frosty breaths of Nicky and another character are clearly visible, indicating scene was shot on unheated location set - functioning restaurant kitchens are always hot.
When Anna Scott is shot, Nicky Santoro tilts her head and the blood begins to dribble out of her mouth. Actor Joe Pesci places his hand near actress Ffolliott Le Coque's throat immediately after this is done, and Le Coque visibly swallows twice, even though her character is supposed to have just been killed.
When Nicky goes into Anna Scott's kitchen to murder her, he puts the left side of her head into a headlock and fires the gun into the right side several times. Unless all the bullets lodged in her head, which is highly unlikely at such close range, they should have exited her left-side head and penetrated his left arm or the window curtains on his left, but there is no sign of bullets exiting.
Before Nicky and Dominick are shot, they have their hands tied behind their backs. When Dominick is shot, his hands suddenly appear in front of him. However, when he falls backward into the grave, his hands are again tied behind his back.
Near the end of the movie, Ace is shown getting into his car and the driver side window is down which can be clearly seen as he closes the driver side door. The next time this shot is shown, (presumably the same shot, as he is narrating about the steel plate under the driver's seat) the driver side window is shown rolled up as the door closes.
When Nicky's gang hits Dominick at the ambush, Nicky is untouched and yet when they strip Dominick's clothes, Nicky can be seen with blood all over his face. However, Nicky was hit in a deleted scene (some versions of the film retain the scene).