When supposedly playing blackjack, Ben and Sera are sitting at a Caribbean Stud Poker table.
During their first "real" date in a restaurant, a guy with a blue and white shirt passes them in the same direction twice in within three seconds.
When Sera is performing oral sex on Ben in his motel room after he first meets her, her back is visible, and it has no scars on it. Later, when the two of them are in bed after Ben's drunken rage at the casino, he slides up her top to see the scar on her back (which is not possible to be there at this spot).
When Ben is driving to Las Vegas he is alternately wearing a shirt with cuffs and a cardigan-type zip up jumper with no cuffs.
The toilet paper is folded when Sera first sits down to urinate. The next shot of her sitting on the toilet shows that the toilet paper isn't folded any more.
Yuri is supposed to be swearing in Latvian on the phone. In fact, he speaks gibberish.
Ben flips out and overturns a blackjack table in a casino. The tables in casinos are fixed to the floor to minimize the risk of someone stealing chips by "accidentally" overturning the table and scattering them on the floor.
At the gas station while the men looking for Yuri are talking on the phone, the subtitled translation says "Were 30 miles outside of Las Vegas", omitting the apostrophe in "we're".
Ben solicits a prostitute who steals his wedding band. Several scenes later, when he is being fired, he is wearing it again. However, the opening scenes of the movie are not in chronological order. When the ring is seen again, Ben also receives the severance check that he cashed at the bank in the previous scene.
When driving through Las Vegas, Ben finishes a bottle of Vodka; two minutes later there is liquid in the bottle again. Since he is severely alcoholic, it can be expected that it's not necessarily the same bottle; he also may have opened a second one.
Ben has an outburst during the blackjack scene, and the waitress behind him falls on the floor even though Ben never actually comes in contact with her.
The checks (casino chips) in play, on the dice game in particular, are unlabeled. Those are hard plastic play-at-home chips. Every gambling joint has the name and denomination of their checks on a round label in the middle of their, usually clay, checks or sometimes a hard, slippery composite check with a metal insert about the size of a dime. The checks are labeled for obvious security reasons.
A camera and several crew members are reflected in the glass door when Sera leaves the casino after spitting on the security guy.
At the 22 minute mark Ben is leaving Los Angeles for Las Vegas. In reality he is driving south through downtown when he should be driving east. 10 seconds later he's driving north on the same freeway when he should be going east.