Leonard Snart and Mick Rory attack the Santini crime family in episode 1x15 "Out of Time".
A groom shows his betrothed a beautiful heirloom necklace that she will get after they are married in episode 5x05 "All Doll'd Up".
Iris and Barry dress fancily to attend a fundraiser hosted by Theresa Merkel to ask her about her son in episode 5x05 "All Doll'd Up".
A group of satanists perform a mock-scarifice and later Lucifer and Chloe arrive to question them about the actual dead girl in episode 1x12 "#TeamLucifer".
Maze arrives at Amenadiel's place while he is brooding and tries to convince herself to kill him after they sleep together in episode 1x12 "#TeamLucifer".
Stein tries to convince Jax to join him but ends up drugging him when that doesn't work in pilot episode "Pilot, Part 1".
Snart, Rory, and Ray break into a mansion to steal the dagger only to find out it belongs to Vandal Savage in pilot episode "Pilot, Part 2".
The Cigarette Smoking Man takes a phone call about the Tad O'Malley situation in episode 10x01 "My Struggle". Mulder confronts the Smoking Man in his mansion in episode 10x06 "My Struggle II". The Smoking Man talks to Reyes about his plan and Mulder arrives but finds that the Smoking Man has already left in episode 11x01 "My Struggle III".
In a flashback, Jules waits at home with Maddie so she can introducer her parents to her new wife in episode 1x07 "Frog-Bikini-Eiffel Tower".
Jules and Richard talk their way into a fancy country club in their search for some legal advice in episode 1x07 "Frog-Bikini-Eiffel Tower".
Mel picks up Maggie from a military-themed party and later Maggie is kidnapped and brought to a party to celebrate her acceptance into Kappa in pilot episode. Maggie visits Parker at his frat house and finds him injecting himself with some sort of drug in his room in episode 1x07 "Out of Scythe". Maggie parties with Lucy and finds herself talking to Parker who is bartending in episode 1x12 "You're Dead To Me". Appears in 1 more episode.