I think the line was "Holy F-ck". Not s major moment so PG-13 is about right.

The scene where Amy Adams and Jeremy Renner's characters enter the spacecraft for the first time. After Jeremy leaps up into the walkway/tunnel he turns around looking toward the ground and exclaims "Oh f". Albeit, though, the word is muffled and could be hard to make out by some viewers due to the fact that he's 1. wearing a special suit and 2. the musical score helps drown it out a bit. It wasn't loudly exclaimed in the slightest. You've got nothing to worry about. Do keep in mind, too, that there is a use of h-ll, btard, and a couple of "omg's". Very clean and light PG-13 film. Great movie by the way. Highly recommend it!