The Earth-X Snart is chasing Siren X when he is taken back to Earth-1 by Cisco and Barry in episode 4x19 "Fury Rogue".
The team takes Neil Borman out of the facility where he is being held in a modified hazmat suit and put him in a truck to transport to an A.R.G.U.S. facility in episode 4x19 "Fury Rogue".
Siren X heads the team's plan to move Neil Borman from a great distance and decides she needs a nuclear meta of her own in episode 4x19 "Fury Rogue".
Cecille and Ralph attempt to get a list of people treated from a FEMA administrator but are initially thwarted in episode 5x06 "The Icicle Cometh".
Source: BC Hydro
The team brings Cassandra to a nuclear storage facility to contain the potential explosion in episode 1x15 "Cor-ai".
Liv and Clive head to a gun range to question Harley Johns about some posts he made on the anti-zombie forums in episode 3x04 "Wag the Tongue Slowly". Liv and Ravi infiltrate a meeting of zombie believers at the gun range in episode 3x08 "Eat a Knievel". Ravi listens to the anti-zombie group's plans and attempts to delay them from kidnapping a zombie in episode 3x09 "Twenty-Sided, Die". Appears in 2 more episodes.
Dirk finds himself held captive by Friedkin and repeatedly tested for psychic abilities in episode 2x01 "Space Rabbit". The Kellum Knights attack Black Wing looking to kill the Boy in episode 2x09 "Trouble Is Bad". Dirk races across the facility to find the Boy in episode 2x10 "Nice Jacket".
Source: BC Hydro