(at around 27 mins) McKay is confronted by Major Lorne and his men. When McKay turns around and they show him from the front, his tablet PC is in his right hand. The next shot looks over McKay's shoulder and shows Lorne firing a stunner at McKay with the tablet PC in his left hand. Then the tablet PC ends up an improbably long way to the right from where McKay dropped it.
McKay states that using a jumper to dial the stargate won't work because the gate will not maintain a stable wormhole without the control crystal. In Vengeance, Sheppard uses a dart's dialing device to use a stargate that Michael had taken the control crystal from.