Jordan Rhodes, the Terriers' leading marksman in last season's promotion campaign completed an £8million move to fellow Championship side Blackburn on Friday, but there was little sign Simon Grayson's men were missing him in Suffolk early on.
Midfielder Adam Clayton crashed in the opening goal from the edge of the box after the hosts had failed to clear their lines to give Huddersfield the half-time lead.
But the Tractor Boys hit back in the second half when captain Luke Chambers, a summer recruit from Nottingham Forest, poked in his first goal for the club after Darryl Murphy had headed the ball back to him.
Michael Chopra produced a clinical finish to edge the hosts in front, but striker Vaughan soon levelled matters before being presented with a golden opportunity to seal all three points seven minutes from time when Huddersfield were awarded a controversial penalty.
Vaughan saw his first spot-kick saved by Scott Loach but thought his follow-up effort had gone in as it hit one post before rolling along the line and striking the other. Referee Mick Russell thought otherwise and the game ended all-square.
It was the hosts who should have gone ahead in the early stages when Murphy failed to make Lee Martin's excellent work down the left count.
Murphy only returned to Portman Road on deadline day after agreeing a season-long loan move from Celtic, and he was given the perfect chance to reintroduce himself to the home faithful, only to steer wide.
Debutant Paul Taylor was clearly thriving in his new surroundings and a mazy run culminated in a fizzing shot which goalkeeper Alex Smithies repelled.
But the hosts were made to pay when they failed to fully clear a corner nine minutes before the break.
After initially heading Oliver Norwood's delivery out, Ipswich managed to block two efforts from the edge of the box before Clayton was presented with a third bite of the cherry, driving through a forest of players to register the game's first goal.
Ipswich had looked dangerous from set pieces and another free-kick proved fruitful as Chambers levelled matters just after the hour mark.
A hanging back-post delivery from Andy Drury was nodded across goal by Murphy and Chambers managed to bundle the ball home.
There was large slice of fortune in the goal which put Ipswich in front 10 minutes later as Chopra somehow latched onto Martin's through ball. There was nothing lucky about the finish, though, as he emphatically beat Smithies.
Huddersfield fought back as Vaughan, on loan from Norwich, was on hand to tap in a sweeping move.
Then came the game's big talking point as Jack Hunt tumbled under a challenge from Murphy. Referee Russell initially waved away Huddersfield's appeal before having a change of heart following a conversation with his assistant.
The controversy did not end there, though, as Loach parried Vaughan's spot-kick straight back to the striker, who struck both posts with his follow up before Ipswich scrambled clear.
Vaughan was convinced the ball had crossed the line between striking the woodwork twice, but Russell ignored his protests, ensuring the sides shared the spoils.