Those missed opportunities loomed large for the Dons in the fifth minute when Carlisle took the lead, Graham Kavanagh cutting a ball back from the by-line for Kevan Hurst to cut inside a defender and fire neatly home. Kavanagh then volleying over the top six minutes later from a Vincent Pericard lay-off as United were on the attack once more.
1-0 became 2-0 to the Blues after 17 minutes when Kavanagh's free-kick in, after a foul on Matty Robson, seemed to glance off the shoulder of Pericard and into the far corner of the net. Pericard then only three minutes later repeating the feat to make it 3-0, this time the ball did go in off his head but it was a scruffy effort that bounced and bobbled its way in.
With 33 minutes gone a dangerous Kavanagh low cross in saw no-one prepared to gamble on it from a Carlisle perspective, the Dons then making it 3-1 two minutes later, Chadwick smashing the rebound home from inside the box after a Devaney pass had been blocked straight out to him.
The Buckinghamshire outfit then made it 3-2 in a mad spell in the match on 37 minutes when, after his initial shot had been saved by Adam Collin, Chadwick stabbed the ball into the net following a Baldock knock-down on the rebound. Collin then saving United moments before the break when he made a fantastic stop to tip round the woodwork a fierce effort from Jason Puncheon.
It was 3-3 only two minutes into the second-half though when Harte was left looking like he was running in quicksand as Baldock flew past him and finished crisply past Collin from 18 yards out as Harte bizarrely looked to blame Collin for the goal. Dons goalkeeper Willy Gueret then pushing an Adam Clayton shot wide on 52 minutes, Robson, at close range, shooting wildly over from Kavanagh's resultant corner.
The Dons soon got on top though and went close a few times around the hour-mark, efforts from Devaney and Chadwick both being denied by some excellent work by Collin. The United goalkeeper was left watching in the 62nd minute though when Baldock made a good run forward before thumping a long-range drive inches wide.
Carlisle weren't to be denied though and somehow they retook the lead midway through the second period when Kavanagh's corner into the box was touched off by Pericard for Joe Anyinsah to smuggle the ball home from no more than three yards out. The visitors were pushing forward well now and Gueret had to make good saves from Robson and then Anyinsah.
He was helpless though on 80 minutes when Pericard, one-on-one with the Dons stopper, somehow pushed his shot, from an Anyinsah pass, onto the top of the crossbar and over when it seemed easier to score. Danny Swailes then failing to level matters again for the Dons shortly afterwards when, well placed, he headed a Puncheon corner wide, that flag-kick coming after Puncheon himself had seen a drive saved by Collin.
Hurst then hit what was pretty much the last shot of the game wide for the visitors before they were reduced to ten men in injury time. Midfielder Tom Taiwo sent off for a second booking after hoofing the ball away as the Dons looked to take a late free-kick quickly in their fruitless search for an equaliser.