Space Cowboys and Pitch Black (spoilers)
Like many enjoyable SF movies, these are okay if you switch off your critical scientific faculties for a while.
Space Cowboys has someone surviving a terminal speed impact with the Moon, which is quite amazing. And it suffers from the "NASA picks a bunch of guys they would normally not touch with a ten-foot-pole to go into space" syndrome (see also: Armageddon) Otherwise, it does seem to work at being credible.
Pitch Black is a good thriller, once you get past the idea of light-fearing creatures evolving on a planet which only sees darkness once in many years.