In the beginning of the movie De Niro's crew are doing a job, robbing an armor car by slamming a track against it.
The job starts with Weingro (Slick) getting on a truck, driven by Cheritto.
The thing is that Cheritto doesn't know Weingro, and has to identify him with a code word. Also as they drive towards the location, Weingro is trying to conduct small talk and ask basic questions about the crew, which irritates Cheritto.
This doesn't make sense. Why would they do a job with some guy that they don't even know? Why didn't they spend some time together before the job in order to get to know each other better (Weingro and the rest of the crew)? Also wouldn't they have to prepare for the job together before the execution? So how it is possible that Weingro and the crew know nothing about each other?

Another unrealistic thing happens after the job. After Weingro needlessly kills the guard of the armor truck, De Niro decides to whack him.
They meet up in a busy restaurant where De Niro slams Weingro's head against the table out of anger, drawing the attention of the diners. Afterwards they go out to the public parking lot where De Niro decides to shoot Weingro, only to be distracted by a passing police car, which Weingro uses for his advantage and succeeds to escape.
Again... why? Why meet up in a public restaurant, and not at some discrete location without a crowd? Since when a group of robbers meet up at a public place after executing a job in order to discuss business? Besides that why to spook Weingro? Why not act cool and then take him to an isolated location and whack him there? Why make a scene in a busy restaurant slamming his head against the table? Doesn't make sense.
Edit: also they could have killed Weingro on the same day after the job, they were all in the escape car together. Didn't make any sense to wait a few days in order to do it in a public parking lot.

(please do not tell me that those are not plot holes. I don't claim they are. Notice the flair).

Edit: looks like somebody posted this 13 years ago https://www.reddit.com/r/movies/comments/d1wac/i_think_i_found_a_substantial_plothole_in_heat/?utm_source=share&utm_medium=mweb .