When Iron Man was announced for Spider-Man: Homecoming, fans knew there would be some other crossovers from the Marvel Cinematic Universe in store for them. There are more than a few easter eggs to be found in the trailer footage, but one specifically gives reference to Pepper Potts in Iron Man 3.
In the film Pepper (played by Gwyneth Paltrow) is sleeping nest to Tony Stark (Robert Downey Jr.) in a t-shirt that says "I lost an electron" with the other saying "Are you positive?" Tony is also present throughout the opening Homecoming trailer, and it turns out that Peter Parker (played by Tom Holland) has a similar fashion sense, as he's wearing the same shirt underneath his jacket as the two walk down a hallway (with Jon Favreau's Happy Hogan in the background). You can view it below (via Reddit).
You can check out all of the easter eggs here.
A young Peter Parker/Spider-Man (Tom Holland), who made his sensational debut in Marvel Studios' Captain America: Civil War, begins to navigate his newfound identity as the web-slinging superhero in Spider-Man: Homecoming.
Spider-Man: Homecoming is directed by Jon Watts, from a screenplay by Jonathan M. Goldstein & John Francis Daley and Watts & Christopher Ford and Chris McKenna & Erik Sommers, and stars Tom Holland (In the Heart of the Sea), Michael Keaton (Batman, Birdman), Zendaya (K.C. Undercover), Donald Glover (The Martian, Community), Jacob Batalon (North Woods), Laura Harrier (One Life to Live), Tony Revolori (The Grand Budapest Hotel), Tyne Daly (Cagney and Lacey), Bokeem Woodbine (Fargo), with Marisa Tomei (My Cousin Vinny, The Wrestler), and Robert Downey Jr. (Iron Man, The Avengers). It also includes Martin Starr (Silicon Valley), Kenneth Choi (The People vs. O.J. Simpson), Michael Mando (Better Call Saul), Selenis Leyva (Orange is the New Black), Isabella Amara (The Boss), Jorge Lendeborg, Jr. (Graceland), JJ Totah (Liv and Maddie), and Hannibal Buress (30 Rock).
Doctor Strange is in theaters now, followed by Guardians of the Galaxy Vol. 2 on May 5, 2017. Next up is Spider-Man: Homecoming on July 7, 2017, with Thor: Ragnarok landing on November 3, 2017. Black Panther debuts on February 16, 2018, followed by the eagerly anticipated Avengers: Infinity War on May 4, 2018. Ant-Man and the Wasp hits on July 6, 2018, with Captain Marvel finally hitting theaters on March 8, 2019.