Ralph and Sue break into the bank posing as Joe and a police officer to access the safe deposit box but Sue betrays him in episode 6x12 "A Girl Named Sue".
They escape through a hole in the alley behind the building. A group of bank robbers attack a bank and kill a police officer in episode 1x06 "Legacies".
Eric Dunn shoots a bank guard while fleeing a robbery in episode 5x07 "Vigilante".
Source: What's Filming
The team arrives at a bank robbery to find one of the thieves dying on the ground in episode 5x07 "Vigilante".
Felicity and Oliver invite all of their friends and family to a postponed wedding reception in episode 6x09 "Irreconcilable Differences".
Astra talks her way into the vault with Constantine and then Nora knocks out the teller allowing them free reign over the soul tokens in episode 4x16 "Hey, World!".
Sargon the Sorcerer is almost finished robbing a bank after summoning Beebo as a distraction but his plan is foiled when Barry and Sara arrive in episode 5x01 "Crisis on Infinite Earths: Part Five".