A sportsbook sits across the parking lot from MetLife Stadium, but East Rutherford didn’t feel like Las Vegas until Raiders fans took over the building in the second half.

The crowd of 70,080 had its share of black and silver jerseys at kickoff, but it was never clearer that the Jets were playing a “road” game at home in their 38-33 loss Sunday than when left tackle Olu Fashanu committed a false start on third-and-5 as Raiders fans made it difficult to hear Geno Smith barking out signals.

“It’s on me,” Fashanu told The Post. “I’m not going to say it’s because of the crowd. No matter what the environment is, I have to be locked in and hearing the snap count. Kudos to the Raiders fans. Obviously, they travel well, but that’s not an excuse. I have to be better.”

The Raiders hadn’t visited the Jets in a non-COVID-19-restricted season since 2019, so local fans of one of the NFL’s national teams waited a long time for Sunday.

And Raider Nation’s excitement surely increased after a surprise 3-0 start to the season — and didn’t dissipate during a four-game losing streak.

“They had some fans in the building and we have to handle it,” receiver Garrett Wilson said. “It’s a home game, regardless. Protect our home turf. We’re sitting there at 2-6. We have to give our fans a reason to come out. I get it. As a team, we have to operate regardless of the noise.”

Raiders cornerback Eric Stokes was flapping his arms in the fourth quarter to urge the fans to get louder. They complied and drowned out the home crowd.

“The silver and black was out,” head coach Klint Kubiak said. “We heard them, they were loud, and they supported us from pregame, through the game, and especially in that fourth quarter. That was really special, so I’m really grateful for our fans.”

How hard was it to operate as an offense when you are expecting silence at home?

“There’s only 22 people on the field at the end of the day,” receiver Adonai Mitchell said. “The fans are always going to be there.”

Running back Braelon Allen claimed that he didn’t hear the noise.

But first-year Raiders quarterback Kirk Cousins called the MetLife takeover a “pleasant surprise.”

“I got hit on one of the touchdowns and didn’t know that Jalen [Nailor] scored, but I could hear our Raiders fans,” Cousins added. “I’m trying to discern whether we scored or not by looking up at the crowd because I’m on my back, and I see the Raiders fans up cheering. I’m like, ‘I guess we scored.’”

Jets head coach Aaron Glenn thought the Raiders’ first-half 95-yard kickoff return for a touchdown — to take a 14-13 lead — flipped the crowd.

“It just sucks the life out of the whole building,” Glenn said. “Because I thought our fans were in it. I thought they did a great job of creating momentum for all of us.”

The Raiders and their fans seized it away.