The visitors looked in total control in the first half after going in front in the 13th minute when midfield man Martin Woods converted from the penalty spot after James Coppinger had been brought down in the box by defender Jordan Spence.
Rovers could have been further in front by the interval but both Coppinger and John Oster squandered good chances.
The visitors looked to have the points firmly in the bag when former Scunthorpe favourite Billy Sharp headed them further in front from close range after 62 minutes with his first goal for the South Yorkshire club since joining them on a season-long loan from Sheffield United.
Sharp, once the darling of the Glanford Park crowd, was suddenly the villain as he collected a yellow card for celebrating his goal.
Things began to turn sour for the visitors seven minutes later when Oster was red carded for an off-the-ball incident which left Scunthorpe midfielder Grant McCann needing stitches to a facial injury after the game.
That allowed the home side back into the game and they reduced the arrears after 72 minutes when club skipper Cliff Byrne headed powerfully home from the corner.
Things then went from bad to worse for Doncaster and three minutes from time they were reduced to nine men when midfield anchor man Quinton Fortune was sent off for a two-footed challenge on Byrne.
Suddenly Rovers found themselves hanging on and only a great reaction save from keeper Neil Sullivan kept out a header from substitute Garry Thompson.
But Scunthorpe were not to be denied and grabbed an equaliser from the penalty spot in the second minute of stoppage time after a handling offence by Woods.
Doncaster protested long and hard at the decision but McCann stepped up to convert from the spot for his fourth goal in successive games.
It stretched Scunthorpe's unbeaten run to five games as they recover from a poor start to the season.
But it left Rovers with their sixth draw in nine games and looking angrily in the direction of referee Keith Stroud, who also flashed eight yellow cards in a game that was far from physical.