Oliver, Diggle, and Felicity attend the Starling City Cancer Society's annual auction to draw out the Dodger and Felicity ends up getting one of his collars around her neck in episode 1x15 "Dodger". Felicity and Oliver put on a fake wedding to draw out Carrie Cutter in episode 4x16 "Broken Hearts".
Sara and Hunter attend an event hosted by Vandal Savage in an attempt to recover Carter's body in episode 1x03 "Blood Ties".
The Legends infiltrate a Nazi-controlled bar after learning that the JSA is in danger in episode 2x02 "The Justice Society of America".
Source: What's Filming — Twitter