It's hard to keep much undercover nowadays and Mark Ruffalo's Tuesday night (October 10) Instagram Live session is proof of that when the actor accidentally streamed audio from the Los Angeles world premiere of Thor: Ragnarok.

Ruffalo, who stars in the new film, took to the El Capitan Theatre stage when a recording of castmate Jeff Goldblum introduced the film along with his co-stars Chris Hemsworth and Cate Blanchett. As per the Hollywood Reporter, about 2,500 people were active on the stream as he pointed his phone to the audience to capture the moment and then later put the device in his pocket without logging off Instagram for a whole 15 minutes. While it was just an audio-only stream, Ruffalo's session went on until about 8:15 PM when he stopped the live feed. 

Tuesday night's mishap is ironic since Marvel had audience members at the theater "turn off their mobile devices and allowed security staff to lock them in sealed pouches before entering the theater." After the incident, the actor took to Twitter to make a joke about the incident, writing, "I felt bad you weren’t there with me. I snuck you in. In my pocket," he wrote in response to the Hollywood Reporter article. "All kidding aside... I’m sorry @Marvel. Can I have my phone back?"

Thor: Ragnarok hits theaters on November 3 in 3D, IMAX and IMAX 3D.

Photo: Getty Images