The majority of the Development Squad had been involved in the County Cup success against Windscale but they were brought back to earth with a bump on returning to league action at the Sheepmount.
League leaders, Unisun, consolidated top spot by securing the points despite conceding the opening goal early in the first half.
Josh Palmer had put Reds ahead with less than five minutes on the clock and they held on to the slender advantage for over an hour. Palmer (inset) had also scored against Athletic in the earlier meeting last month.
But two spectacular goals from David Barnes, with a controversial penalty sandwiched in between, swung the game in favour of the Carlisle outfit.
Barnes was grounded when he hooked the ball into the net for the equaliser and Reds hardly had time to recover from that blow when they found themselves behind.
Ben Atkinson converted the harshly awarded penalty, sending Scott Paden-Gale the wrong way from the spot.
Some poor defending led to the third goal which Barnes spectacularly despatched with a sublime swerving shot.
Reds are on the road again this week, travelling to Gosforth for league action.
Team: Scott Paden-Gale, Hayden Percival (Ben Wade), Zach Martin, Robbie Wilson, Dan Whitehead, Louis Webster, Lewis Moore, Luke Whitehead (Milo Cooke), Ben Davidson, Josh Palmer, Hayden Rae.