Of course it's unconvincing and wildly unrealistic. Welcome to Hollywood movies, where spy satellites can read handwritten letters and sports cars can pull bank vaults down the street.

Spoiler alert, from the reviews I've read I know the basic answers to those questions. A meteor shower bumps his pod open, and he's a "3rd class" passenger, he doesn't have authorization from the computers to operate the sleeper pods. The crew who would are locked in another section of the ship and he doesn't have…

Having never read any variation of the script, I don't know. Scripts typically go through a lot of revisions even when they're solid to begin with. There's an awful lot of wrong ways to go with this kind of story, and also a lot of more interesting ways it could have been done.

It was on the script black list (a list of "most liked" scripts) way back in 2007. It had been in development hell for years, essentially because of how creepy the twist is. I understand the ending has gone through several revisions.