The UFC prez tells TMZ Sports the flub was a mix of his production team dropping the ball, a technical issue, and the unpredictability of live television.

The way Dana explains it ... there was a plan in place to show Trump sitting near the Octagon. Cameras were supposed to pan from some big-name celebrities to the former Prez ... but things didn't go according to script.

“We were getting ready to show him right between the co-main and main events, I think you remember that we showed OBJ. We showed OBJ, then it was supposed to go to David Spade, 2 Chainz, and then the president, and we had some kinda glitch in the truck. Then the Conor fight ended up ending in the 2nd round so we never got a chance."

White continued ... "Let me tell you what, massive f*** up by my production team, but ya know, it’s live TV and these things happen.”

We obtained video of DT arriving at T-Mobile Arena in Las Vegas midway through the main card ... and you see Trump being greeted by Dana and getting a nice ovation from the packed crowd.

But, Trump was never seen on the broadcast ... leading some to speculate there was something nefarious going on with the ESPN broadcast.

Dana says that's NOT the case ... telling us any former president deserves to be shown on TV, regardless of political affiliation.