Dr. Melfi's facial bruises disappear is the middle of the show and reappear by the end.
When Tony Soprano is talking to Ralph Cifaretto outside the pizzeria, the positioning of Ralph's coffee cup and spoon keeps alternating between shots.
When Tony is chopping wood he is using an ax that also has a hammer head on the other side. The camera shows him swinging down, then shows the blunt hammer head side hitting a piece of wood and it splits in two anyway.