When the dog is running away with the skeletal arm, not only does it sometimes have the hand to the right, instead of to the left, it also changes from being a bare arm at the start, to a sleeved arm when it's dropped.
Near the beginning of the episode, when Charlie is shaving during the conversation with Hurley, the little smudge of blood on Charlie's chin vanishes and reappears in between shots.
Just before Hurley begins driving his rounds in the Microbus near the end of the episode, the side door on the bus is open; in the very next shot, it is closed.
At the start of the episode, Charlie is shaving, however during the morning and day, Charlie's beard growth changes from stubble to clean shaven to stubble again.
After Hurley gets the van started, Vincent alternately appears and then disappears in the remaining scene with the van.
When Danielle shoots at Kate, John and Sayid in the woods, she fires three shots from a bolt-action rifle in less than one second. This is an impossible feat by even the most highly trained rifleman.