Chris Pratt once gave Marvel fans a rare behind-the-scenes glimpse from the sets of Avengers: Endgame, despite strict rules against filming on mobile phones. The actor, who played Peter Quill, aka Star-Lord, secretly recorded a video featuring several major Avengers cast members.Pratt later shared the footage on Instagram after the film's release, calling it a “really illegal video” and explaining that he wanted to capture what he described as a once-in-a-lifetime moment.Key HighlightsChris Pratt secretly filmed a video on the Avengers: Endgame set.Mobile phone filming was not allowed during production.The footage featured several major Marvel stars together.Chris Evans jokingly warned Pratt about being in “big trouble.”Pratt shared the video after Avengers: Endgame was released.The actor said he wanted to preserve the rare moment with the ensemble cast.Chris Pratt's 'Illegal' Avengers: Endgame VideoWhile filming Avengers: Endgame, the cast was reportedly not allowed to record videos or take photographs on their phones because of the film's strict secrecy.Pratt nevertheless pulled out his phone and filmed a behind-the-scenes video showing several members of the cast gathered on set. The footage included stars such as Chris Evans, Robert Downey Jr., Chris Hemsworth, Paul Rudd, Mark Ruffalo, Jeremy Renner and Chadwick Boseman.Pratt could be heard joking that the video was “really illegal.” Chris Evans then appeared in the footage and jokingly responded that Pratt was in “big trouble.”Why Did Chris Pratt Record the Footage?Pratt explained that he was amazed to see so many members of the Avengers cast together in one place.He said he wanted to capture the moment because he believed the large group of stars might never be together in the same room again. The actor also described the gathering as a special moment for everyone involved in the film.The footage was particularly notable because of the secrecy surrounding Avengers: Endgame. The movie contained major plot developments, and Marvel had taken extensive measures to prevent spoilers from leaking before its release.Avengers Cast Appeared TogetherThe video showed a large group of actors relaxing and preparing on the set. Among those visible were Chris Evans, Robert Downey Jr., Chris Hemsworth, Paul Rudd, Elizabeth Olsen, Jeremy Renner, Benedict Cumberbatch, Danai Gurira and other members of the ensemble.Some actors also reacted to Pratt's post after it was shared. Vin Diesel, who voices Groot in the Guardians of the Galaxy films, praised Pratt's decision to capture the moment.Chris Pratt Shared the Video After the Film's ReleasePratt posted the video on April 29, 2019, shortly after Avengers: Endgame opened in theatres. Waiting until after the movie's release helped avoid revealing some of the film's major surprises.The behind-the-scenes footage also showed how tightly controlled production was because of the movie's spoiler-sensitive storyline. Pratt's decision to secretly record the cast offered fans a rare look at the actors between takes.The video quickly attracted attention online, with reports at the time noting that it had been viewed millions of times.A Rare Marvel Behind-the-Scenes MomentChris Pratt's video remains one of the memorable behind-the-scenes glimpses from Avengers: Endgame. While the footage was recorded against the production's phone-filming rules, Pratt said his motivation was to preserve a unique moment involving a large part of the Marvel cast.The clip also captured the atmosphere among the actors while they prepared for one of the film's major sequences, giving fans a look at the ensemble beyond the finished movie.