Rovers deservedly led at Belle Vue with a 66th minute goal from summer signing Paul Heffernan, but the costly blunder came 10 minutes later.
Goalkeeper Andy Warrington and substitute Stephen Roberts hesitated over a bouncing ball that could easily have been cleared and it led to a goalmouth scramble from which Izale McLeod snatched the equaliser.
The visitors had been the better side at the start as Doncaster began shakily with Warrington having to save with his legs at the near post to deny Aaron Wilbraham in the fifth minute.
Wilbraham flicked on a free-kick five minutes later to set up a chance for McLeod but his shot on the turn flashed narrowly wide.
But it was all Doncaster for the rest of the half, although Warrington had to make another brilliant save on the stroke of half time to prevent Dean Lewington scoring against the run of play.
Summer signing Sean Thornton looked impressive in midfield for Rovers and he was involved before Heffernan had a shot well saved in the 18th minute.
But, although they were outplayed at times, the Dons worked tremendously hard in all areas with McLeod always a threat with his pace upfront.
Rovers finally made the breakthrough in the 66th minute when Heffernan, a £125,000 summer signing from Bristol City, repaid part of the fee with a splendid header from James Coppinger's left-wing cross.
But they were unable to add to this score, despite looking well in control, and the blunder in the 76th minute caused red faces all around.
McLeod deserved the credit for striking in opportunist style after making space for himself with some tricky footwork.
Rovers raised their game in the closing stages but Paul Green missed a great chance with the goal gaping and then a brilliant cross from Thornton, which was begging to be converted, sailed past everyone.