George Porter opened the scoring for the home side in just the 11th minute and Jack Holland added another before half-time.
But then the floodgates really opened in the second half as Joshua Rees and Adam Mekki got on the scoresheet. Orient did pull one back through Macauley Bonne's first goal for the club.
However, it got worse for the away side as Jack Holland netted his second and then Brett Williams added the gloss with a sixth late on.
It's unbelievable. I'm ecstatic, delighted for the players, supporters, the board, my playing staff because they put in a shift," said manager Neil Smith.
"We had a game plan and to a man, probably overachieved. They've given me everything since they walked through the door on the 27th June and today was just everything we've been asking for.
"We do know it's only one game and we've got Hartlepool on Saturday, and we have to get their feet on the floor again.
"That was the perfect performance apart from the goal against. We wanted players who wanted to be here. They're hungry to improve, learn and work for each other, I think that showed today."