The ending was very exciting and, although far more low-key than the UK's pouches-of-coloured-powder-in-the-fire approach, I think it was more dramatic as it was stripped down to the bare bones.
I'm no actor, but one of the 'celebs' they had on who was an actor, and was therefore considered highly suspect by his fellow players, made the point that he's a good actor when he has a script and has done work on developing his character (and I think a good director is a definite plus). As he said, none of those things were true for him in the game. He was being himself, it was all he could do.
So I'd image that the same would apply to Sam, if he really is a would-be actor. We were watching the real Sam.
I rewatched the episode (6 or 7) when they did the challenge of carrying the silver bars up a hill. There were nine players at that stage and they carried a total of 17 bars, worth $34,000, up the hill. Sam carried three that we know of. He also traded three (for a key to the armoury and two drinks), so he lost the team $6K. So one person out of nine appeared to have traded all of his silver bars for personal gain, actual or potential, when his team mates could know nothing about it. Why did he do that? He went to all that effort and then handed it over to Rodger (and the amusing Daniel. I do like him). When Rodger announced at the end that they'd forfeited $16k for their 'bar bill', Sam made lots of shocked gasping noises, accompanied by suitable facial expressions.
Apart from the gasping and facial contortions, I don't think that was acting at all. I think that was the real Sam, though why he did that only he can know. This, coupled with his weird small-boy thing of making a gun out of his fingers and shooting people from day 1, calling himself 'The Sheriff', wearing the cowboy hat, his total narcissism and his reactions at the end, which were possibly just as much about realising other people had differing desires to his as to losing the money, make me think he's someone I'd give a very wide berth to.