In the end Andy Frame's side won the Sectional League Cup group match comfortably enough against a makeshift Kilsyth side who were without a management team following the resignation of Keith Hogg and with trialists in several positions.
Rangers made a couple of early chances and then almost gifted an own goal at the other end, but trialist keeper, McNeil saved the day.
Then Franny Kelly had to go off after a clash with a United player and it was obvious that he could not continue with former favourite Phil Dolan taking his place.
Cumbernauld were now making most of the running and a good run by Martin Shiels in a corner from which Jamie Watson headed in the opening goal.
Then Dolan was involved in an incident which ended up with both him and David Waters being yellow carded, much to the annoyance of the Kilsyth fans.
It was a fairly even game in terms of possession but United always looked more dangerous going forward and could have added to their score on several occasions, only good work by McNeil kept them out until just before half-time when Davie Dickson scored with a fine shot.
The second half was only five minutes old when United went three up; Willie Wells got the ball with the defence wide open and gave McNeil no chance with a shot to the roof of the net.
David Waters was replaced by Henderson and at last Rangers began to get a grip on the game.
Iain Diack got one back just after the hour mark and it was a much more even game now, although Cumbernauld always looked comfortable on the ball and were never really in danger of not getting the points.
Another card for Waters, although he was now in the dugout, for making a comment on the referees' performance and also one for Denholm completed a miserable night for Rangers.
Next up for Kilsyth is a home match with holders Kirkintilloch Rob Roy on Saturday. Cumbernauld have no game this weekend.