When Matt is talking with Anderson in the Long Branch, Kitty brings Matt a beer with a big head of foam. Immediately thereafter the glass is full of beer with no head. It remains that way until Matt gets up to leave, when all of a sudden the glass is partially empty, even though it was seen full immediately before.
As Matt is in the jail cleaning his gun and talking to a doc about his plans to leave in the morning to accompany Anderson, the camera pans too far up and the top of the back wall of the jail can be seen, with studio lights above it.