O Brother, Where Art Thou? - S4-E15
Character mistake: During the opening scene, while Lex is talking to Lena he says he was quoting Epicurus from 230 years prior. Epicurus died in 270BC, making that quote around 2300 years old.
O Brother, Where Art Thou? - S4-E15
Factual error: While the location of National City is never revealed, it is generally accepted that it is located in the US. But all the helicopters used to fly Lex around are Canadian.
Answer: Yes, s02e22. As Kara leaves her office, she said "go get them, Supergirl" to herself. After season 1, the show switched from a CBS production to a CW production and filming moved from L.A. to Vancouver. Flockhart isn't really a fan of traveling to shoot, and didn't want to be away from her family for so long.
Bishop73