Unlike the other Arrow episodes, it was not filmed in Vancouver but in Chicago, which served as a stand-in for Gotham City. Some scenes in this episode were the same locations used in The Dark Knight (2008) trilogy , in which Chicago was one of the handful of cities which would create the composite fabric of Gotham.
Kate says Wayne's R&D (Research and Development) guy still works at Wayne Enterprises, a reference to Lucius Fox.
Kate Kane is named after the co-creator of Batman, Bob Kane.
In addition to crossing over with The Flash (2014) and Supergirl (2015), the episode also serves as the backdoor pilot of Batwoman (2019). Ironically, the series premiere itself actually serves as a prequel to Kate's appearance here.