I kind of liked the shout out to Star Wars and Star Trek. If you could do it without ruining the flow of a story, why not? :D

Or why the Doctor had to recock the gun at the Master when he'd already cocked it at Rassilon... and then cocks it *yet again* to turn around again?

Because the Doctor doesn't know how to actually use a gun? And do you think The Doctor called him 'Rassilon' as an insult, or did the Time Lord's really reincarnate their monstrous founder?