Momoa posted the image on his Instragram which shows him with his guitar and Gal Gadot (attemping?) playing the drums.
"[Gal Gadot.] What a women what a wonder. Love ya mama," Momoa said.
Gal Gadot stars as Wonder Woman, with her solo movie coming out prior to Justice League on June 2, 2017.
Jason Momoa stars as Aquaman, with his own movie coming out following Justice League on July 27, 2018.
"Justice League" has a November 17, 2017 release directed by Zack Snyder starring Ben Affleck as Batman, Henry Cavill as Superman, Gal Gadot as Wonder Woman, Jason Momoa as Aquaman, Ezra Miller as The Flash, Ray Fisher as Cyborg, J.K. Simmons as Commissioner Gordon and Willem Dafoe as an Atlantean.