Embiid's 32 points made it the seventh game in a row he has reached at least 30, while Harden posted a triple-double of 16 points, 14 assists and 10 rebounds.
The Sixers looked to be coasting at one stage, finding themselves 26 points to the good, but the Trail Blazers made life a little trickier towards the end.
Rivers' team got the job done as they improved to 29-16 in the East, behind only the Boston Celtic and Milwaukee Bucks, though he was certainly not completely satisfied.
He was particularly irritated by the Sixers' poor handling of the Trail Blazers' trapping, and he was not impressed by how spread out his players were.
Asked how they coped with respect to trapping, Rivers said: "Poorly, but we also took advantage of some of it as well.
"I didn't think trapping was that hard, our spacing was horrendous, and we're great at spacing most nights, but tonight we kept leaving two guys on the other end.
"I'm hoarse from yelling, just getting one to cut through and we basically didn't do it. We got away with three or four more than I thought they could've had. But that's easy to fix."
In letting Portland back into the contest somewhat in the second half, Rivers felt there was a hint of complacency in the Sixers' performance.
As such, he surmised they are still not at a stage where they can consider themselves anything more than a "good" team.
He added: "There's no lesson, the lesson is execute. I just thought we didn't.
"You get leads sometimes and they're hard, NBA leads shrink quickly and then you get complacent, and I think we did a little bit of that.
"But in that, one thing I like is we kept playing defense, and that's a good sign.
"I think we're good, and I think we can be really, really good. But we have work to do.
"We can't expect to come in and just show up and win, we have to go out and do something about it."
Nevertheless, with the likes of Embiid and Harden in their arsenal, the Sixers have the kind of star quality that can drag them through the mud even when they are not at their optimal level as a unit.
That is not lost on Embiid.
"I think from the beginning it was easy," he said of linking up with Harden, who joined from the Brooklyn Nets last February.
"When you've got two guys with high basketball IQs, you can figure it out everything easy.
"So, it's all about just playing off of each other. We've been doing a wonderful job of doing that."