Lee Johnson's side hit the headlines this week when they came close to signing convicted rapist Ched Evans, although the move fell through amid pressure from external sources.
Goals from Jabo Ibehre and George Elokobi either side of the interval appeared set to put a difficult few days firmly behind Oldham, but Joseph Mills' sending off following a fracas proved pivotal.
Substitute Nathan Tyson reduced the deficit three minutes after Mills' 75th-minute red card, before James Coppinger netted deep into second-half stoppage time to earn Doncaster a share of the spoils.
Jay Emmanuel-Thomas and Derrick Williams added further gloss to a comfortable triumph after the interval, with Steve Cotterill's men climbing back above Swindon Town, who do not play until Monday.
McLeod netted a second three minutes into the second half to give the home side a much-needed cushion, but Harrold's hopes of an unlikely clean sheet were dashed when Will Grigg headed home 14 minutes from time.
Dele Alli's last-gasp strike ensured the Dons did not leave empty-handed.
At the other end of the table, Crewe Alexandra are out of bottom four for the first time since August following a 3-1 victory over Gillingham, Yeovil Town stay bottom after their 2-0 defeat at Barnsley, and Colchester United claimed an impressive 2-0 win at Peterborough United to boost their own survival chances.
In the day's remaining fixtures, Fleetwood Town won 1-0 at Leyton Orient, and Scunthorpe United triumphed 4-1 at Walsall.
