Crawley Town skipper Jimmy Smith scored an injury-time goal which secured their League 2 status next season.
Reds took the lead in only the 11th minute in spectacular style when Collins smashed a brilliant shot from outside the area.
Collins then made it 2-0 after 26 minutes from the penalty spot.
But Carlisle fought back to 2-2 at half-time with goals by Jabo Ibehre and former Reds striker Jamie Proctor.
The visitors looked to have won the game when Reggie Lambe made it 2-3 in the 59th minute.
However Joe McNerney supplied Smith for a vital injury-time equaliser which brought terrific celebrations from both the players and fans.
Crawley fielded an unchanged side from the which lost 1-0 at Accrington Stanley last weekend.
Josh Yorwerth and Matt Harrold returned to the bench after suspension and injury respectively.
Carlisle had the first chance to score on nine mibutes when Jamie Devitt hot the post and skipper Danny Grainger went narrowly wide on the rebound.
Reds took the lead in glorious style just two minutes later when the ball came to Collins and he fired unstoppably into the top right hand corner of the net.
The visitors went immediately on the attack with Lambe shooting low but straight at keeper Glenn Morris.
Moments later United were on target again as a cross was headed on goal by Proctor but the chance was again saved by Morris.
Collins handed Crawley a 2-0 lead with only 26 minutes gone from the penalty spot.
After being brought down by Macaulay Gillesphey in the box, Collins stood up and calmly put away with a shot to the bottom right corner for his 22nd goal of the season.
Crawley had to make the first of two early substitutions forced by injury when Josh Yorwerth replaced central defender Mark Connolly.
Carlisle pulled a goal back when a long ball over the top by skipper Danny Grainger was lifted over Morris by Jabo Ibehre.
Reds made their second substitution after Morris, who was wearing a bandage on his head, went down and received treatment, and then came off, replaced by reserve keeper Yusuf Mersin.
Carlisle went into half-time level at 2-2 as Proctor headed his side back on to level terms from a cross from the right by Grainger.
Reds were first out of the blocks in the second half as Dean fired low from the left but Carlisle keeper Mark Gillespie saved.
Carlisle completed their comeback by taking the lead when Proctor crossed from the left and Lambe put away from short-range.
Enzio Boldewijn set-up Josh Payne for a powerfully-hit speculative effort from 25 yards which was struck just inches wide.
Smith scored Crawley's third to snatch a draw from the jaws of defeat to the delight of the home fans.
REDS: Morris, Young, Payne, Connolly (Yorwerth 27), Boldewijn, Smith (capt), Blackman, Collins, McNerney, Djalo (Roberts 69), Cox
Unused subs: Harrold, Clifford, Lelan, Murphy
CARLISLE: Gillespie, Grainger, Joyce, Raynes, Proctor (Tomlinson 75), Gillesphey, Ibehre, Bailey, Devitt (O'Sullivan 79), Lambe (Brisley 88), Liddle
Subs: Adams, Miller, Crocrombe, Nabi
REFEREE: Darren Deadman
ATTENDANCE: 2,003 (224 away)
CRAWLEY OBSERVER MAN OF THE MATCH: