Xander leaves Anya at the wedding and is shown walking around in the rain. Cut shots back at the wedding show that it is sunny outside (window behind Buffy, Dawn talking outside to party guest)
During Anya and Xander's final conversation when he tells her he can't marry her, the hair on his forehead changes between shots.
As the manager shows Xander into the motel room, you can see over the top of the set.
When Anya is rehearsing her vows in the dressing room, a man's legs and boots can be seen on the right side of the screen.