That lead quickly doubled when Glenn Murray notched the Cumbrians second shortly afterwards. McGill made his way down the right wing to the Rochdale by-line and laid the perfect ball back for Murray to finish crisply from eight yards out, as a shellshocked home side were left wondering what had hit them.
Rochdale worked hard to get back in the game though when good work between Kyle Buckley and Joe Thompson fed the ball into Nick Blackman. Striker Blackman got a good connection on a powerful drive from fully 22 yards out but fortunately for the Blues it was straight at Anthony Williams in the Carlisle goal.
After 32 minutes United had already all but sewn the game up however when they went three goals to the good. McGill curled a free-kick in from the left-hand side with his right-foot which Glenn Murray got an extremely feint touch on as the ball flew across the face of goal and into Rigby's net at the back-post.
Two minutes later 'Dale had a half-chance to try and mount a comeback but Matt Williams' curling effort from the edge of the United box went inches over the Cumbrians crossbar. The Blues looked like scoring every time they went forward in the first-half though against, more or less, a Rochdale youth team with their first-team playing Grimsby Town just 24 hours later, and that's what happened when they made it 4-0 just before the break.
Ex-'Dale centre-half, and occasional goalscoring centre-forward Simon Grand, hit a long ball up from the back for the front two of Glenn Murray and Rivers to chase. The ex-Crewe man got there first as he outpaced the home defenders and Rivers, in a one-on-one with Rigby, was able to smash the ball past a dejected Rochdale keeper to pretty much seal a Carlisle victory after only 43 minutes.
The home side had obviously had a big flea in the ear during the fiteen-minute interval from their reserve team boss Tony Ford, he of 938 appearances in the Football League fame, as they came out fired up after the break. United defended resolutely though against a spell of Rochdale pressure, with Grand even finding time to head a corner from the right by half-time substitute James Earl just inches past Rigby's far-post with 50 minutes on the clock.
The Blues soon began to stamp their authority in the game once more though and Earl went close just after the hour-mark when he tried a speculative effort from 20 yards out. Rigby had read the danger in the home goal however and was able to get down quickly at his near-post to make an excellent diving save.
A fifth goal for the visitors was looking inevitable against a young and tiring Rochdale side by this stage and it came after 70 minutes through centre-half and youth team skipper Dan Kirkup. Another great delivery in from a flag-kick on the right-hand side by Earl gave an unmarked Kirkup, celebrating the announcement of his third-year YTS contract offer earlier in the day, a simple chance to head home past Rigby from close-range.
'Dale did have a chance to bag a consolation goal in the closing stages of the match when home substitute Nathan Taylor took possession away well from Kirkup just outside the Carlisle box. Crossing the ball in low Taylor was able to find fellow replacement Ben Wharton but the Rochdale frontman could only slice his shot wide of the target. The last name on the scoresheet would be a United one though when Earl made it 6-0 to the Blues in the 86th minute.
Pete Ferris, who had taken to the field in place of Glenn Murray with twenty minutes to go, sent Earl racing clear down the right-hand side as the Rochdale defenders looked for an offside decision. The assistant referee kept his flag down though and Earl was able to fire home past the hapless Rigby as the United midfielder made his way into the 'Dale box to complete the scoreline in a rout for the Blues.
A great result for the Carlisle second-string who have performed well together as a unit all season and that cohesiveness saw them go back to the top of the table on goal difference from Preston North End tonight. United also have a game in hand on the Lilywhites but that comes round quickly as the lads only have 40 hours or so until they face bottom-placed Wrexham at Buckley Town FC on Wednesday afternoon. The three Blues trialists all performed well in the Rochdale game and will feature again in the Wrexham match.
Rochdale line-up :
Lloyd Rigby, Michael Murray, James McDonagh, Kyle Buckley, Krystian Bowden, Krystian Liptrot, Matthew Kay, Callum Warburton, Joe Thompson, Matt Williams, Nick Blackman.
Substitutes :
Raphael Evans, Danny Woodhall, Nathan Taylor, Ben Wharton.
United line-up :
Anthony Williams, Ben Christensen, Matthew Blake, Simon Grand, Dan Kirkup, Luke Joyce, Brendan McGill (Gary Baker 75), Nicky Platt, Glenn Murray (Pete Ferris 70), Mark Rivers, Simon Hackney (James Earl 46).
Unused substitutes :
Adam Bradley and Ashley Combe.
Trialist information
Raphael Evans (centre-half from Burnley)
Ben Wharton (striker from Stockport)
Ben Christensen (right-back from Sunderland)
Luke Joyce (central midfielder from Wigan)
Nicky Platt (central midfielder from Burnley)
Updated Reserve Team Table : Click here
Updated Reserve Team Results : Click here