Revealing mistake: During the card game at Smiley's house, there are several shots from slightly to the left side of Smiley where you can see his moustache is false and is not completely glued down on the right side of his mouth.
Revealing mistake: The streets and the sidewalks are always wet, despite the fact that it's sunny the whole time.
Suggested correction: Sometimes there are many minutes, or even an hour, in between scenes that would have passed in universe. More than enough time for a quick rainstorm to roll through off camera.