Hutcherson, 22, revealed to Entertainment Tonight he "snuck into Comic-Con" donning the mask, passing through the crowd effortlessly before taking a selfie in front of the Hunger Games booth. He also used the mask to scare his co-star.
"Josh came into my room today and scared the life out of me in a mask," Lawrence, 24, told the outlet when asked if she wore a disguise to enjoy the convention. Hutcherson shared his selfie with ET before Lawrence commented on the physical status her masked colleague was in.
"You were really sweaty," she said before he walked away. "I was about to go out the door and we're both going to the same event. I was like are you going to shower?" Lawrence said. "I don't think he did."
Thursday's Hunger Games Comic-Con appearance was the Lionsgate franchise's last, as Mockingjay Part 2 prepares for release in the fall. Lawrence called the series life-changing; "I feel like it will always be part of me," she added, according to Variety.
Hutcherson reportedly seconded that, saying working on The Hunger Games has "been the most incredible movie making experience," and thanked fans for supporting the franchise over the years.
When asked about the final day of shooting for the series' final installment, the Serena actress admitted she didn't say anything because she was too emotional. However, she said director Francis Lawrence -- who was also part of the panel -- delivered a "beautiful speech."
"That night we held each other and slept like puppies," she said.
Mockingjay Part 2 hits theaters Nov. 20.