Captain America: Civil War was a defining moment for the MCU, as it drove the Avengers apart, setting the stage for their fractured state in Avengers: Infinity War. It also delivered one of the best action set pieces in the entire history of Marvel Studios, the battle between Team Cap and Team Tony at the airport in Germany.
This sequence was also an important moment of firsts, mainly the introduction of Tom Holland's Spider-Man and Paul Rudd's transformation from Ant-Man into Giant-Man. The latter is interesting because it almost included the onscreen debut of Hope van Dyne's Wasp (Evangeline Lilly), something we were waiting to see since the theatrical release of Ant-Man in 2015.
"Some of you may know I did a whole bunch of keyframe illustrations based on an early script draft of Civil War," Park wrote on Twitter. "Wasp was at one point going to make her debut in this movie. It was fun but I’m glad they held out to properly introduce her in Ant Man and the Wasp."
The "What If?" of Wasp's involvement in the airport battle is addressed in Ant-Man and the Wasp when Scott asks Hope if she would have come had he asked her.
"I guess we'll never know," she says. "But if you had, you'd have never been caught."
Still, if Scott was never caught, we would have had a much different Ant-Man sequel, since the entire plot hinged on his house arrest, a direct result of his stealing Pym technology and helping Captain America & Co. in Civil War. Conversely, there was nearly a Cap cameo in Ant-Man and the Wasp, but that's a story for another time.
The idea of introducing the Wasp was inevitable ever since the post-credits scene of the first Ant-Man, where Hank Pym (Michael Douglas) tells his daughter that it's time she took up the mantle that her mother (Janet van Dyne) vacated all those years ago. Upon viewing the winged suit, Hope says four words: "It's about damn time."