The visitors stole the lead after 25 minutes, but then saw their day fall apart as Orient hit them with a five-goal blast. To complete their misery John Dempster was sent off 20 minutes from time.
Orient, who had suffered two successive home defeats, started well but fell behind against the run of play. Gary Mills threaded the ball down the right to Drewe Broughton and the Rushden striker powered into the area before slotting the ball wide of Glyn Garner and into the corner of the net.
It marked the start of three goals in four minutes as Orient were quickly back on terms.
Joe Keith crossed from the left, Lee Steele flicked the ball on and Orient's new captain John Mackie smashed the ball home at the far post.
Two minutes later the hosts surged ahead. Craig Easton's delicate chip set up Steele, who drove the ball in from 12 yards.
Orient continued to pile on the pressure and were rewarded with a third goal to complete a deadly 10-minute spell.
Wayne Carlisle floated in a corner from the left that Mackie headed down and Steele reacted first to fire home his second of the game.
After the break Rushden skipper Dave Savage was replaced by Neil McCafferty and for a while the visitors threatened a revival, as the dangerous Chris O'Grady was denied by Garner's smart stop.
But 20 minutes from time Dempster went crashing into the Orient keeper and was shown a red card by referee Ray Olivier.
Orient cashed in on their numerical advantage and four minutes later, stretched their lead following good work from two of their substitutes.
An excellent run down the left flank from Daryl McMahon was rounded off by a pinpoint cross, which was headed home by Jabo Ibehre from close range.
Then Easton put the icing on the Christmas cake with a fifth goal - a speculative lob from 25 yards.