A penalty from Wayne Rooney (14) and a blistering effort from the outstanding Paul Scholes (68) earned United an eighth straight league win for the first time since 2009, but the damage was done to relegation-haunted QPR before Rooney’s opening goal.
United striker Young was clearly offside when he collided with visiting midfielder Shaun Derry in the visiting penalty area on 14 minutes.
There appeared to be minimal contact between the players, but Mason pointed to the spot without appearing to consult with his linesman before sending Derry off for denying Young a goal-scoring chance.
Derry appeared to give a rueful smile as he headed up the tunnel before Rooney planted the ball beyond Paddy Kenny low to the goalkeeper’s right for the opening goal.
It is the second straight home game in which United have courted controversy over a penalty incident.
Midfielder Michael Carrick - who cracked a shot against a post from 30 yards out with Kenny beaten - escaped without conceding a penalty after appearing to trip Danny Murphy in his own box late on in a 1-0 win over Fulham at Old Trafford last month.
United were never under any serious threat against the 10 men after Derry departed with Scholes walloping the ball under the diving Kenny from 25 yards out to seal the win with 22 minutes left.
QPR deserve credit for refusing to buckle despite being a man light for over 75 minutes, but were forced to play a containing game with Kenny diverting a shot by Rafael onto his bar on 59 minutes before spreading himself to block a shot by Danny Welbeck a minute later
Adel Taarabt picked the pocket of Rafael midway through the first period only to watch Jonny Evans race back to make a fine intervention, but Taarabt was culpable at United's second goal as he needlessly squandered possession to enable Scholes to drill home the third goal of his career against QPR - the second was 16 years ago.
Mark Hughes’s QPR side remain out of the bottom three ahead of Wigan and Blackburn Rovers on goal difference only. They are fourth bottom of the standings, and in the thick of a relegation fight to avoid returning to the Championship a season after winning England's second tier.
QPR have only picked up two points in their last nine away matches in the Premier League since winning 3-2 at Stoke City in November. They are the only Premier League side without an away win in that period. For United, there are no such problems.