20146 100a Avenue as Al's Bar
Mon-El follows the real Hank Henshaw outside as and fights him as the virus is released inside the bar.
“Medusa” Filming Locations
The team must fight against Cadmus which is preparing to release a virus that will kill every alien in National City.
Supergirl episode “Medusa” was filmed in Langley, Surrey, & North Vancouver in Canada.
Surrey City Hall as L Corp
Cyborg Superman breaks into the lobby of L Corp to steal the isotope needed to use the Medusa virus but is thwarted by Kara.
Source: What's Filming
Vancouver Wharves as Port of National City
Lillian takes Lena to the port to launch the rocket carrying Medusa and is confronted by J'onn and Kara.