I love it when DC characters mention the abandoned warehouse thing.
I once set out to track the warehouse thing across every show on the CW, and OMG IT WAS SO MUCH WORK. Those DC shows are full. of. warehouses. You'll be unsurprised to hear that ARROW was once King of the Warehouses (my favourite is the one ACROSS FROM CITY HALL) but SUPERGIRL has pulled ahead by a huge margin thanks to the warehouse bar its characters frequent.