According to a criminal complaint, Abdulrahman Oriyomi's flight reservation had been canceled, and the boarding pass he had appeared to be a forgery.
Police say surveillance video showed him speaking with a TSA agent the morning of May 18. He was then escorted to another TSA booth where his picture was taken, and he was allowed to pass through security.
Michael Matranga, a former Secret Service agent who now runs the consulting group M6 Global Defense, said TSA agents should never have allowed Oriyomi through security without a valid boarding pass.
"I think this is a pretty significant breach, not just because of the fact that he ended up on the plane; it's the multiple layers and failures to even get on the plane," Matranga said.
Police say Oriyomi then approached a gate and tried twice to scan the fake boarding pass, but to no avail.
More than an hour later, they say he showed up at another gate where United gate agents were scanning boarding passes.
Police say Oriyomi walked right past the agents while they were busy with other passengers.
"They're not paying attention to his diversionary tactics. They're distracted, they're not situationally aware," said Matranga.
Police say Oriyomi hid in the plane's restroom as it taxied to the runway, and that a passenger alerted flight attendants to his presence.
Once the flight crew realized he wasn't supposed to be on the plane, it returned to the gate where it was met by police, an explosive device unit and the FBI.
Matranga said all of that could have been avoided had Oriyomi been stopped from the beginning at the TSA screening checkpoint.
"At a very minimum, those agents that were directly involved and probably that whole cadre of agents at the airport need to be retrained on policy and consistency in policy," he said.
Oriyomi was questioned the same day and given a trespass warning, but charges were not filed until June 1, and he wasn't arrested until Friday morning.
The Harris County District Attorney's Office said HPD didn't approach it about filing charges until June.
HPD told ABC affiliate KTRK that officers didn't have enough to charge Oriyomi initially. However, after an investigation, he was charged with impairing or interrupting the operation of a critical infrastructure facility.