At the Thor: Ragnarok red carpet premiere, star Mark Ruffalo treated the Marvel Cinematic Universe fanbase to a sneak peek of the movie, albeit an unsanctioned one. The star accidentally livestreamed a portion of the film on Tuesday night from the Los Angeles world premiere after he forgot to switch off his Instagram live.

According to The Hollywood Reporter, Ruffalo -- whose role as the Hulk in this film is set to kick off a new character arc -- hit the stage with his co-stars before the screening began and used his phone to offer online fans a closer look at the night's proceedings. However, when Ruffalo put the phone in his pocket, the social media platform was still running, allowing his audience to indulge in audio bytes from the event.

RELATED: Thor: Ragnarok Is First of Four ‘Very Unique’ Marvel Films

Around 2,500 people were on the stream listening to Ruffalo and the crowd laughing at scenes from the Taika Waititi-directed film, with audio from the movie clearly audible. Fans were even commenting as to how long it would take Ruffalo to realize the error of his ways and cut the stream, which came to an end a few minutes later.

It remains unclear if someone told him his stream was still running or if it cut out on its own, but Ruffalo's gaffe may well lead to Marvel Studios keeping their stars' cellphones closely monitored, just like they do for guests and press at similar screenings. At the end of the day, Marvel execs will surely be happy it wasn't one of the movie's rumored post-credits scenes.

Arriving November 3, director Taika Waititi’s Thor: Ragnarok stars Chris Hemsworth as Thor, Tom Hiddleston as Loki, Cate Blanchett as Hela, Idris Elba as Heimdall, Jeff Goldblum as Grandmaster, Tessa Thompson as Valkyrie, Karl Urban as Skurge, Mark Ruffalo as Bruce Banner/the Hulk and Anthony Hopkins as Odin.