It was a second defeat by the Yorkshire club four days after Tuesday's Papa John's Trophy loss and meant Stags had lost all four clashes with Harrogate, who went top with this victory.
In contrast it was a third League Two defeat in a row for Nigel Clough's men and also their worst performance so far this season.
Stags simply failed to get into gear all afternoon against the high-pressing visitors, failing to capitalise on taking a third minute lead.
Trailing 2-1, they then lost skipper Ollie Clarke and midfielder Stephen Quinn after a 73rd minute decision when Clarke was adjudged to have been the last man as he brought down the excellent Jack Diamond, Quinn also dismissed after allegedly felling Josh Falkingham in the ensuing melee.
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But the visitors thoroughly deserved the points and the score could have been worse were it not for three fine saves by Nathan Bishop.
Mansfield made two changes from the defeat at Swindon with Burnley loanee Richard Nartey coming in for an immediate debut in place of Farrend Rawson while Danny Johnson was replaced up front by Rhys Oates.
Oates and Stags made a dream start with a goal after just three minutes.
McLaughlin floated in a free kick towards the far post where Oates expertly steered home a pinpoint finish across the keeper.
But within two minutes the game was all square again as Thomson's left wing corner found McArdle who powered home a header from six yards.
McLaughlin played a fine one-two with Hawkins in a promising burst down the left, but Oxley was down quickly to smother the dangerous low cross.
Nartey marked his debut with a booking after only nine minutes after he was late with his challenge on Thomson.
In Stags' next raid Hawkins set up a shooting chance for Lapslie 20 yards out, but his finish was always rising well over.
Bishop had his first save to make on 25 minutes as a half-cleared corner reached Pattison whose low drive was blocked by the keeper's legs.
Harrogate then struggled to clear a teasing Gordon cross, but when the ball broke for Quinn he was well over with his snapshot.
Gordon went down under a challenge in the box on 36 minutes but the referee was unimpressed and decided it was a dive and booked the Stags man.
Lapslie was added to the book two minutes later for persistent fouling after his late block on Falkingham.
Page caught Maris late on 41 minutes to also draw a card from the referee.
On 42 minutes McLaughlin sent in a fine 24 yard free kick that Oxley did well to tip over the bar.
Stags were furious when the ball appeared well out for a home throw but play was waved on and Clough's men had to defend two successive corners instead.
As we entered the second of three added minutes the visitors grabbed the lead as Armstrong helped on a right wing cross by Pattison and Muldoon was there to tuck the ball home from eight yards.
Clarke whistled an early 20-yarder well over the angle after the break.
On 50 minutes Thomson sent a free kick into the home wall and when the ball spun towards Armstrong, an offside flag was up as he headed home.
Hawkins then saw a looping header from Stags' second corner of the half drop onto the roof of the net.
Oates then set up Gordon on the right, but he delayed his shot and finally saw it blocked for a corner.
Hawkins sent a header wide from a McLaughlin cross on the hour as Mansfield continued to probe for the equaliser.
Muldoon almost profited from a flick-on into the box, but Nartey did well to stick with him and force him into a soft shot straight to Bishop.
Ex-Stag Burrell was booked for his 66th minute foul on Oates, but Mansfield were unhappy play had been continued with no obvious advantage.
Johnson replaced Lapslie and seconds later McLaughlin headed over from Gordon's long free kick.
Falkingham tripped Oates on 70 minutes to become the afternoon's sixth booking.
The game exploded on 73 minutes as Diamond tried to race past Clarke and was fouled. He was well outside the box but the referee decided Clarke was the last man and sent him off.
That sparked a melee in which Falkingham went down and after the dust settled, the referee sent off Quinn as well.
On the resumption Thomson sent the free kick straight at Bishop.
Bishop also did well to turn away a Muldoon finish as the Harrogate man tried to chip him with no expected offside flag.
At the other end Hawkins was wide from a McLaughlin cross.
On 81 minutes Bishop again saved superbly, his legs denying Armstrong from close range.
But it was game, set and match seconds later as Thomson headed home Page's corner from close range at the near post.
Diamond was booked for a foul on 89 minutes, Maris added for his trip in the fifth of six added minutes.
STAGS: Bishop, Gordon, Nartey, Hewitt, McLaughlin, Maris, O. Clarke, Quinn, Lapslie (Johnson 68), Oates (Rawson 76), Hawkins (Bowery 82). SUBS NOT USED: Shelvey, Burke, Sinclair, Stirk.
HARROGATE: Oxley, Page, Falkingham (Kerry 76), Burrell, Thomson, Pattison (Power 84), Muldoon (Orsi 87), Hall, Diamond, McArdle, Armstrong. SUBS NOT USED: Cracknell, Fallowfield, Martin.
REFEREE: Paul Howard.
ATTENDANCE: 4,599 (155 away).