The lens on Sue's ex-husband's camera changes between shots when he is taking pictures of the drug lord executing a captive. When seen head on it is a 500mm mirror lens and from the side it is a 50-300 zoom lens.
After Sue is rescued from Long Island, Mick is in the kitchen preparing breakfast. In the background, we can see that the front door to the apartment is a few inches open. Seconds later, Detective Brennigan walks in and has to open the door first.
When Mick, Leroy Brown, and Rat's gang are driving from the city to Long Island, Rat is driving the car. We hear a grinding sound, followed by Leroy telling Rat to take it easy on the clutch. However, we never once see Rat's hands leave the steering wheel to shift the car.
The fuse on the dynamite stick does not ignite before Mick removes the lit cigarette from it. Obviously a different stick (or the same one properly ignited with a Bic lighter) was used in the next shot, when the fuse is visibly smoking.