Near the end of the episode, there's a shot of Charlie's right hand without the weight belt wrapped around it, then a moment later it's back on.
Charlie decides he will swim down to the Looking Glass Station in order to remove the jam which prevents radio signals from leaving the island. In Season 1, Charlie said he could not swim during an incident where someone was drowning. But Charlie knows his swimming ability is limited as evidenced by his flashbacks and his reluctance to tell Desmond how long he can hold his breath for. Thus, it is logical for Charlie to swim down to the station because he knows it to be a one-way trip.
When Alex is skinning the rabbit, she learns Ben will attack a day earlier than planned. Ben returns the pistol to Alex's bloody hands. She immediately jumps up and runs to Karl to have him warn the islanders of the impending attack. She hands over the pistol to Karl with clean hands.
Before Charlie gives Hurley a hug, the foot of a crew member and a part of a camera is visible.
In the flashback, Drive Shaft are supposedly on their way to Clitheroe, but the countryside doesn't look like Lancashire, or anywhere else in the UK. Also, the front number plate is yellow. Only the rear plate is yellow on UK cars, and the front is white.
During the flashback before Charlie helps Nadia, at the crossing a taxi drives on the right side of the road with STOP written on this side. As this is supposed to be London, it should be on the left.
The survivors have a map of The Looking Glass station, but it never occurs to anyone to sever the power feeding the station, presumably through the cable that they found on the beach.
Charlie leaves his "DS" ring in Aaron's crib, a very dangerous item to leave in the crib. As Charlie had been helping take care of Aaron, he would be aware of keeping choking hazards away from the baby.