United's under-18 side were in Youth Alliance Cup action as they played the first of their three group games against Blackpool on Tuesday afternoon.
But they were ultimately undone by an unbelievable second half spell of three goals in the space of just four minutes which left the visitors with a comfortable two-goal cushion.
United dominated the opening ten minutes and they could have been ahead with just three minutes on the clock when a deep free kick from Galloway found Branthwaite unmarked. He got his head to it but he couldn't keep it down.
A winding run from Charters brought a stinging low delivery as the Blues stayed on the front foot, and Kerr was inerested as it spilled out of the keeper's hands. A quick recovery prevented the striker from stabbing the loose pieces home.
More good balls into the box caused problems for the Seasiders and Barnes was disappointed when he jumped highest at the far post to meet another lofted Galloway set piece. His connection lacked conviction and it angled wide of the upright.
There were loud appeals for a penalty when Kerr tumbled to the floor just inisde the box, but they were waved away as Blackpool broke at pace. A low cross had the defence worried but it skipped away to safety as Ward dived low.
Blackpool went in front against the run of play when they burst out of their own half in numbers. Watkinson called for it and he kept his cool as he thumped it past Ward and into the roof of the net.
Carlisle kept their football going, and crosses from Charters and Birch peppered the danger area with Kerr looking to cause a distraction. An excellent move invited Brockbank forward and a crunching 18-yard volley was heading for the top corner until the stopper got his fingertips to it.
The young Blues should have pulled level when Birch stayed deep for a great pass which picked him out in space just seven yards from the target. He tried to guide his effort at the bottom corner but succeeded only in touching it wide of the mark.
It was much tighter after the break, with half chances for both sides, and United started to find gaps as Soper was thrown into the fray. And the big forward put his side right back in it when he surged into the box and let fly with an effort on the run. It found its way over the line as the keeper allowed it to fall out of his grasp and bobble over the line.
The lead lasted just 48 seconds as Blackpool went long from the restart. Bange bullied his way onto the ball and slotted the rebound from an untidy shot home as he somehow kept his feet as he came under pressure.
Two minutes later and it was a mountain to climb for Carlisle when Watkinson latched onto another clip over the top. He left Ward with no chance as he rattled an excellent finish into the roof of the net.
Blackpool saw the game out, as United huffed and puffed, and they took the points home as the hosts now look to their second group fixture - away at Wrexham in a fortnight's time.
United - Ward, Barnes, Wilson, Lightfoot (Kelly 72), Brockbank, Charters (Soper 64), Casson, Branthwaite, Birch (Rooks 80), Galloway, Kerr (Trialist 80). Subs - McLachlan.
Goal - Soper (68)