The U's left it late to snatch a point from the game, with Freddie Sears' penalty cancelling out Elliott Hewitt's second half header at the JobServe Community Stadium.
Colchester United lined up with four changes to the starting eleven, with new signing Charlie Daniels sitting on the bench for the first time since joining the U's.
Coming into the starting eleven was Miles Welch-Hayes, Luke Hannant, Freddie Sears and Noah Chilvers, in place of Tommy Smith, Cameron Coxe, Sylvester Jasper and Brendan Wiredu.
The visitors looked to get on top of the home side quickly after their two wins from the opening two games, with Danny Johnson a dangerman up front.
The former Leyton Orient man should have put his side ahead with eight minutes on the clock, but for a fine save from Shamal George. The U's 'keeper spilled the initial effort from Ollie Clarke straight to Johnson, but made amends quickly to deny the forward from tapping in from inside the six-yard area.
Danny Johnson had another effort on target just before the twenty minute mark, getting his head on a looping ball at the back post, aiming his effort at the top corner. Once again, Shamal George was there to thwart his effort, plucking the ball out and pushing it clear for a corner.
The U's fought back later in the half with Sears and and Hannant going close, but there was an injury blow for Hayden Mullins' side late on as Tom Eastman had to be replaced with what looked like a hamstring injury with ten minutes of the half remaining, with Cameron Coxe coming on to replace him.
It finished 0-0, at half time, with the visitors having the better of the chances in the first half.
Colchester United went close to benefitting from a sloppy Mansfield pass early in the second period, with Chilvers collecting and driving towards goal, but he was caught as he took the effort with the ball deflecting out for a corner.
The U's injury worries were deepened early in the second half, when Ryan Clampin looked to be in some degree of pain after an innnocuous challenge, having to be replaced by new signing Charlie Daniels shortly afterwards.
With fifteen minutes to go, the U's defence was breached as the Stags took the lead in the game. A cross from the left hand side was nodded back across goal and in from Elliott Hewitt at the back post. The goal brought an instant change from Mullins, with Hannant being replaced by Jasper for the final fifteen.
There was late pressure from Colchester United, with Sylvester Jasper and Charlie Daniels taking efforts on goal, the Stags' defence was proving difficult to break through, but the U's earned a late penalty when Frank Nouble was fouled by Stephen McLaughlin.
Freddie Sears stepped up to the spot, and smashed the ball into the back of the net, despite Bishop getting a hand to the ball to send the South Stand into raptures, earning the U's a point at the death.
The well-deserved point means that Colchester United move to seventeenth in the league, with the next opponents, Oldham Athletic losing 1-0 on the road at Bristol Rovers.
Colchester Unites starting XI: George, Welch-Hayes, Clampin (Daniels 59'), Chambers, Hannant (Jasper 74'), Skuse, Nouble, Judge, Sears, Chilvers, Eastman (Coxe 35').
Unused Subs: Turner, Wiredu, Tovide, Beadle.
Mansfield Town starting XI: Bishop, McLaughlin, Hewitt, Rawson, Clarke, Maris, Johnson (Hawkins 82'), Perch, Quinn, Oates (Bowery 87'), Lapslie (Stirk 78').
Unused Subs: Gordon, Shelvey, Burke, Sinclair.