A "splash" or "splash page" is a large, striking image that often takes up two pages in a comic book. Examples from the superhero genre are epic battle sequences involving many moving parts that work together for dramatic effect. For Captain America: Civil War, director Joe and Anthony Russo are whipping out the big guns for their cinematic splash page.

Titans clash as Team Captain America — made up of Falcon, The Winter Soldier, Hawkeye, Scarlet Witch, and Ant-Man — charges into battle across the scorching Atlanta set. Their target is an IMAX camera set atop a roaming car, to be later replaced by members of Team Iron Man. Joe, who’s also directing the two-part Avengers: Infinity War with his brother, explained to CinemaBlend between takes:
This whole sequence is in IMAX. It's about a 15-minute sequence. It's the only one that we're doing on the camera. The camera literally just rolled off the press like a week before we started using it. It's an IMAX 65, so it's the Ares 65. It's a joint camera between Ares and IMAX. We're going to shoot all of Infinity War on those cameras.
The collision pits ally against ally. Black Widow (Scarlett Johansson) and Hawkeye (Jeremy Renner), who fought each other once before in The Avengers, do so again, this time with no mind control to blame. As Natasha dodges swipes from Clint’s bow, Black Panther (Chadwick Boseman) pounces at The Winter Soldier (Sebastian Stan), tearing into his bionic arm with vibranium claws. Meanwhile, Ant-Man works his Pym Particles in front of his own mini green screen. It eventually could look a little like this:

Said Joe Russo:
We're referring to this sequence as the splash panel or the double panel. If you're a comic book fan, you know that any epic book you would open it up, as a kid I would just go through and look at who was fighting who. I'd stand there in the store for 15 minutes until the guy told me to buy the book or get out. You'd just study it and so this sequence is our live-action splash panel or double panel. It's a big epic sequence.
Captain America: Civil War sees the introduction of the Sokovia Accords, governmental action that imposes harsher restrictions on superhero activity. As sides form around Tony Stark (Robert Downey Jr.) and Steve Rogers (Chris Evans), Bucky Barnes comes back into the picture, exacerbating the conflict. Also featured are Frank Grillo as Crossbones, Martin Freeman as Everett Ross, Emily VanCamp as Agent 13, William Hurt as General Thaddeus "Thunderbolt" Ross, Daniel Bruhl as Baron Zemo, and Tom Holland as Spider-Man.

Captain America: Civil War will hit theaters on May 6.