After Jennifer Lopez publicly hugged ex-hubby Marc Anthony onstage in Las Vegas Saturday, she spent the rest of her night making out with boy toy backup dancer Casper Smart behind the scenes. The “American Idol” judge took the stage with Anthony at the Mandalay Bay Events Center as part of a live extravaganza for the divorcing duo’s series, “Q’Viva! The Chosen.” The couple made headlines by taking the stage hand-in-hand before capping off the performance with a dramatic hug. But once the cameras stopped rolling, J.Lo headed to Hyde at Bellagio with boyfriend Smart. Spies said J.Lo made a grand entrance on a scooter, then performed new song, “Goin’ In,” from a DJ booth with Mick Boogie. After dancing on the catwalk with Smart, they were seen in a more secluded lip-lock. “Jennifer and Casper were making out all night,” said a spy, adding that the pair’s posse included “90210” star Evan Ross, son of Diana. Anthony has his own younger hottie, model Shannon de Lima.