Port Vale couldn't have wished for a better start when, after only 14 seconds, Leon Constantine rattled Paul Smith's left post only for Michael Husbands to arrive and slot the ball home for an early lead.
The Forest taunts directed towards former employee Danny Sonner only seemed to spur the midfielder on in the 15th minute when he released a long-range effort that flew over the bar and into the crowd.
The visitors got their first sight of goal two minutes later when Kris Commons received the ball 25 yards out but his shot was comfortably received by the awaiting Mark Goodlad.
Poor defending off a Commons' corner helped Forest to an equaliser when, after Junior Agogo had his shot parried, Ian Breckin emerged from a crowded box to poke the ball over the line.
After a cautious start to the match, Colin Calderwood would have been happy with his side as they looked to be commanding a more dominant position as they ran in for half-time.
Constantine was inches away from restoring Vale's lead when Sonner's right-sided cross was headed back across the face of goal by Richie Humphreys but the striker failed to get the critical final touch.
Forest were by no means settling for a point and came close to a second just after the hour mark when James Perch's swirling cross found Breckin unmarked in the centre but his header lacked enough direction.
Full-back Jason Talbot rescued his flagging side when Breckin was again Forest's outlet for attack with the centre-back forcing an off the line clearance from the youngster.
Referee Rob Lewis turned the game on its head in the 75th minute when, after a seemingly innocuous tackle involving Husbands and Perch, the official sent the Vale striker for an early bath.
Commons made the home fans nervous in stoppage time when a crafty turn on the left of the box gave him room to rocket a shot that bounced out from the underside of the crossbar.