Jordan Cook's brace helped Carlisle come from behind to secure a dramatic victory at MK Dons.
Carlisle's Lee Miller blazed a penalty over the crossbar after Jabo Ibehre handled Jon-Paul McGovern's cross.
Shaun Williams made no mistake with his spot-kick after Dean Bowditch was dragged down by Murphy, but Jordan Cook's neat finish levelled the scores.
A third penalty was awarded in injury time when Tom Flanaghan felled Cook, who duly slotted home the winner.
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MK Dons manager Karl Robinson told BBC Three Counties Radio:
"The officials have got two big things wrong tonight.
"The penalty (for Carlisle's winner) was outside the box. We've seen it twice - it's outside the box
"There was a punch on Stephen Gleeson's face, which we've got video evidence of.
"But we can't go through this season and keep missing chances. It's hard for the back four, they make one mistake and get punished for it.
"We've all got to take responsibility. Me included."
Carlisle United manager Greg Abbott told BBC Radio Cumbria:
"As a manager, you need these type of games to let you know you've got a fighting chance.
"There's a massive amount of credit to our fans, our staff, our players and everyone who travelled down as our group.
"It's an absolutely fantastic night for us, and it's a platform to kick on and grab that little play-off spot, and we've taken on a very good side."
MK Dons 01 Martin 03 Lewington 04 Doumbe (O'Shea - 68' ) 15 Flanagan 07 Gleeson 08 Potter 13 Williams 17 Powell 26 Chadwick (Smith - 75' ) 09 Bowditch 10 MacDonald (Ibehre - 69' ) Substitutes 16 McLoughlin 11 Smith 23 O'Shea 19 Ibehre 46 Hall Carlisle 01 Collin 02 Simek 05 Livesey Booked 06 Murphy Booked 04 McGovern 12 Taiwo (Welsh - 58' ) 17 Noble 21 Berrett 24 Chantler 13 Zoko (Cook - 58' ) 14 Miller Substitutes 20 Gillespie 25 Michalik 07 Welsh 16 Cook 10 Madden
Ref: Mark Heywood