When Winn meets Superman, he asks him how he stopped Lex Luthor when he caused earthquakes in California. This is a reference to Luthor's plans from Superman (1978).
In order to renew the series, Supergirl (2015) was moved from CBS to the CW, which is the home of Arrow (2012), The Flash (2014) and DC's Legends of Tomorrow (2016).
The Martian Manhunter and Superman are not on good terms in this episode. In Smallville (2001), J'onn J'onzz was designated by Jor-El to look after Clark on Earth, saving his life numerous times.
When Cat Grant (Calista Flockhart) summons her new assistant (Andrea Brooks), she yells, "Miss Teschmacher!" in the exact same manner that Lex Luthor (Gene Hackman) yells for Miss Teschmacher (Valerie Perrine) in Superman (1978).
This is the first time Tyler Hoechlin is seen in the role of Clark Kent / Superman on this show. Consequently, it is also the first appearance of his face and voice, i.e. a "full-on" appearance of the character, who up till this point had always been without face and voice.