The scary moment came after Gaga invited Jack onto the stage and they shared a sweet hug, and despite the fall, Gaga assured the crowd afterwards that "everything's okay," telling Jack it wasn't his fault and asking him if he was okay.
She then invited him to sit down on her piano bench. "That was a fall!" she said. "Can you promise me something, can you just forgive yourself right now for that happening?"
Gaga assured Jack it wasn't the first time she's fallen off stage, recalling a time she stage dived and just fell flat, and then comparing the pair to Rose and Jack from Titanic before expertly seguing into "Million Reasons."
Gaga also warned everyone to not be mean to Jack on the internet. "I'm going to be very upset with each and every one of them," she warned. "It's complicated being up here."
At press time, a spokesperson for Gaga could not be reached for comment on whether she suffered any injuries in the fall.
The singer didn't comment about the incident, but did post an image of her grueling post-show rehab routine, which includes a 5-10 minute ice bath, followed by a 20-minute hot bath and another 20 minute stint in a compression suit packed with ice packs.
Gaga is slated to take the stage at the Park Theater at the Park MGM Las Vegas again on Saturday night (Oct. 19).