Jose Mourinho's men are in Los Angeles where they have been preparing for next season.
Game of Thrones, which was first broadcast in 2011, returns this evening for its seventh series.
John Bradley-West, who plays Samwell Tarly of the Night's Watch, and Joe Dempsie, who plays Gendry (who hasn't been seen since season four) popped by.
The pair were seen talking with manager Jose Mourinho and Paul Pogba while they were also given the chance to hold the Europa League trophy, which Manchester United claimed last season.
Bradley-West showed his allegiance to Manchester United by wearing donning their jersey.
Comedian Patrick Kielty, also a massive Manchester United fan, was also at the session.
Mourinho will be looking for improvements from his players following their 5-2 win over LA Galaxy, which was slightly marred by the concession of two late goals as well as a horror miss from new signing Romelu Lukaku.
Manchester United also have pre-season fixtures against Manchester City and European champions Real Madrid in their pre-season tour of the United States.