Spoiler alert: Scarlett Johansson and Chris Evans took their onscreen relationship to the next level today while on the set of their film Captain America: The Winter Soldier in Cleveland, OH. During a romantic scene, shot inside Tower City Center downtown, Johansson pulled Evans in for a passionate kiss on a moving escalator. The scene is surprising, since their characters, The Black Widow and Captain America respectively, haven't been romantically linked yet — and Emily VanCamp was also cast as a Captain America love interest. Do we smell a love triangle? Check out the make-out shots from the upcoming movie, which hits theaters in April 2014.