Galaxy Quest

I have not seen yet TT but the previews it looks like a bunch of players is wrong (or taken in) the roles they play. A similar scenario has been used in Galaxy Quest, where a group of actors in a Trek "Star", as TV / video are mistaken for real heroes ISM.

If this is the case. How come no parallels have been drawn by the critics?

No, they play those roles, but do not know they are not in a movie again. they think so, but the director gets upset with them and dumps in a real war zone, where drug traffickers to get them. they think that the script has changed, but go with it think it will be the greatest movie ever made. sorry for the spoilers. Robert Downey Junior BTW deserves an Oscar nomination for it.

compare it to another film, it's more like the man who knew too little with Bill Murray

In addition to the similarity that they are actors and they are initially unconscious in reality, the stories are completely different. I want to emphasize that Tropic Thunder rated R, some of their jokes are hilarious because of the graphic nature.

Tropic Thunder is also a parody of war films.