Preston had two penalties awarded to them in two mad second-half minutes both were dubious with David Healy having his penalty saved before Richard Cresswell scored his spot-kick.
Kevin Gallen had a free-kick saved by Preston keeper Andy Lonergan who tipped the ball out for a right-wing corner after seven minutes.
George Santos made it 1-0 to QPR after eight minutes from the resultant corner, a right-wing left-foot corner by Lee Cook was met by Santos and his free header flew down into the bottom right-hand corner of the net.
Healy made it 1-1 after 11 minutes when a long kick from Lonergan fell to the Irishman and his left-foot shot went into the top right-hand corner of the net from 15 yards.
Eddie Lewis had a left-foot right-wing corner tipped over the bar by Chris Day for a left-wing corner and Healy had another great chance after half an hour, but his shot rebounded off the keeper's legs.
Paul Furlong hit the bar with a header and the rebound by Kevin McLeod was headed over the bar.
Preston had to replace injured keeper Lonergan and brought on Gavin Ward for his debut in the 40th minute and it was Ward who saved a Gallen free-kick which he knocked round the post for a right-wing corner.
Lewis had a shot saved by Day and a Chris Lucketti header was tipped over the bar, before Furlong hit his own right-hand post with a header.
In the 75th minute Cresswell was fouled in the penalty box by Marcus Bignot and Lewis scored from the loose ball, but the ref disallowed the goal and awarded Preston a penalty. Healy hit the penalty and the keeper saved with his legs.
The ref then gave Preston another penalty when Gino Padula handled.
Cresswell hit his right-foot spot-kick into the bottom right-hand corner with the keeper getting a touch and it ended 2-1 to Preston.