The actors were present at Comin Con festival, San Diego, with the team of their upcoming film "The Expendables 2", a statement said.
When Stallone was asked about how he felt after seeing a montage of his performances, Schwarzenegger came up with a witty reply.
"I actually did better than Sly (Stallone). He's only killed 288 people while I killed 289," Schwarzenegger, 65, said.
He also spoke about his healthy competition with Stallone who is a year older than Schwarzenegger.
"We've always been competing with each other in the last three decades. We ask each other - who killed more people? Who did more brutal killing? Who had more oil on their body," he asked.
Directed by Simon West, "The Expendables 2" is about re-union of old-school mercenaries, where the Expendables are compelled to seek revenge when one of them is viciously killed.
The film is set for a worldwide release on August 17 and will hit theatres in India on August 24.