An angry Steve McClaren blamed poor refereeing decisions for QPR's fifth successive Championship defeat.
The Rangers boss went on to the pitch at the final whistle to remonstrate angrily with referee Tony Harrington after watching Famara Diedhiou net a stoppage-time winner from the spot after he was impeded by Darnell Furlong.
McClaren said: "Their penalty was ridiculous, and when the referee sees it again he will realise what a big mistake he has made.
"The foul was on Furlong, not the other way around. The fact that he took five seconds to give the penalty showed the doubt in his mind.
"We should have had at least one penalty at the other end. What the controversy shouldn't detract from is an excellent performance from ourselves.
"It is a second kick in the teeth for us after missing a late penalty, having come back against Birmingham in the last game.
"I just hope my players can respond again as they did tonight because we have played really well against a team who are on a roll.
"We have to pick ourselves up for a big cup game against Watford on Friday. That's a really important match for us and we don't have long to prepare for it."
Rangers had taken the lead just before the break via Matt Smith, only for the Robins to stage a second-half comeback and claim a ninth successive win in all competitions, with their seventh in the league.
On the back of goals from Niclas Eliasson and Diedhiou's fiercely struck penalty, head coach Lee Johnson was full of praise for his team.
He said: "I can sympathise with Steve McClaren because I am not sure it was a penalty at the end, but we had several other claims and a good goal disallowed.
"There was nothing wrong with Eros Pisano's header, so I think we are both a bit upset with the officiating.
"I can only commend my players for stepping up their game in the second half. They are very proud of the winning run and will do all they can to maintain it.
"We know we are not going to win every game, but if the attitude remains the same we will compete in all of them.
"All the leading clubs in the Championship will have hiccups during the run-in. The table is very tight.
"We also want to go further in the FA Cup and if I make changes against Wolves on Sunday I don't think they will weaken us because our squad is so strong."
