Tony Stark (Robert Downey Jr.) fairly quickly figured out time travel in Avengers: Endgame, and Peter Parker (Tom Holland) may have had something to do with it. Iron Man was so distraught over their devastating loss against Thanos (Josh Brolin) in Avengers: Infinity War that he decided to check out of his superhero gig and live a quiet life with Pepper Potts (Gwyneth Paltrow) and their daughter, Morgan (Lexi Rabe). However, when Scott Lang/Ant-Man (Paul Rudd) emerged and raised the possibility of traveling back in time to collect the Infinity Stone, he was forced to come out of retirement and attempt to bring back those who perished in the snap.

Captain America (Chris Evans) and Black Widow (Scarlett Johansson) were both ready to try anything despite how far-fetched Scott's suggestion was. Things were different for Tony, however - afraid that whatever they were going to try would result in him losing his family. Fortunately, after his initial refusal, it was the thought of potentially bringing back his surrogate son, Peter, that ultimately convinced him to join the Time Heist after seeing an image of the two of them.

Related: Iron Man's Endgame Death Was Even Worse For Spider-Man Than You Realized

Following the surprise visit from his fellow Avengers, Tony was still pondering over the possibility of time travel until he came across a photograph of him and Peter, which was taken on the day the latter supposedly finished his Stark internship. The image didn't seem to have anything unusual to it except for the fake Stark Industries certificate being displayed upside-down. Shortly after that, Tony called to Friday for a late-night session, explaining he "got a mild inspiration." He asked the AI to create a simulation of an inverted Möbius strip, and after a few seconds of rendering, the holographic model clicked, paving the way for him to crack the technology of the wrist devices they used in Time Heist. As unassuming as the goofy upside-down certificate was, it might have actually sparked Tony's idea to flip his Möbius strip model.

Robert Downey Jr and Tom Holland in Avengers Endgame as Tony Stark and Peter Parker

Given how the whole thing played out, there's a good chance that it was an intentional detail. It's known that this was not the first time he attempted to crack time travel as he told Scott during their visit. He explained that he tried everything and nothing worked on his end. The fact that he even mentioned that he suddenly got an inspiration shortly after gazing at the aforementioned image was an indication that the inverted Stark Industries certificate may have inspired his epiphany. At this point, nothing's official since no one has asked this specific question to the filmmakers and they haven't addressed it themselves. It's possible that it's nothing but pure coincidence. However, since directors Joe and Anthony Russo, alongside the writers, peppered subtle Easter eggs throughout Endgame, this could very well be one of them.

Whether or not the said photo helped Tony figure out the specifics of time travel in Avengers: Endgame is unknown. However, what remains is the idea that it was his personal connection to Peter that forced him to suit back up as Iron Man and be involved with Time Heist. And while the MCU will undoubtedly look and feel different without Iron Man in it, his legacy will continue through his contemporaries in the franchise, particularly Spider-Man.

More: Avengers: Infinity War Theory - Each Infinity Stone's Role In Thanos' Snap

Key Release Dates