Several times, Matt Kowalski references the record set by a certain cosmonaut for total time spacewalking, a record the character eventually breaks, though not by the best of circumstances.
That cosmonaut, Anatoly Solovyev, does indeed hold the human spaceflight record and is the only real-life space explorer to have his name dropped in "Gravity."
Solovyev, who at 65 is now retired, ventured outside into the vacuum of space on the first of his 16 extravehicular activities (EVAs) in 1990. Over the course of four of his five flights into orbit, the cosmonaut logged an amazing 82 hours and 22 minutes — almost three and a half days — on spacewalks.
Kowalski says upon passing the record that it's not one he thinks others will be breaking any time soon. Outside the fictional world of the movies, the same could very well be said for Solovyev's achievement.