Mick and Oliver trick their way through the security surrounding the facility in episode 4x08 "Crisis on Earth-X, Part 3".
Amunet and Team Flash interrupt Norvock as he is trying to sell the metal he stole from Amunet's stash in episode 4x21 "Harry and the Harrisons".
SG-1 runs some SGC recruits when they receive a call about a foothold situation in episode 5x13 "Proving Ground".
The team travels to the secret Russian Stargate facility and attempts to defeat some water creatures in episode 4x07 "Watergate".
Source: Richard D. Anderson Website
SG-1 is replaced with mechanical doppelgängers while exploring this factory in episode 1x18 "Tin Man".
SG-1 is forced to work in a factory underneath the domed city in episode 4x10 "Beneath the Surface".
Alex joins Maggie outside a warehouse in a fancy outfit for their not-a-date at the fight club in episode 2x04 "Survivors".
Hank and M'gann are forced to fight each other at Roulette's fight club but are saved by Supergirl and the DEO in episode 2x04 "Survivors".
The Resistance is constructing a portal to another world when they are attacked in episode 3x08 "Crisis on Earth-X, Part 1".
Flynn leads a team that steals the time machine from the lab in pilot episode.
The team takes up refuge in a warehouse where Noah helps patch up Rufus. The team uses the time machine to escape just as Rittenhouse agents arrive in episode 1x16 "The Red Scare".