Parang pilit un crossover.. Ndi msyado exciting like sa flash and arrow..
That's because mahirap yung logistics ng inter-network crossover; they are on 2 different networks, CBS and The CW. Even though CBS partly owns The CW with Warner Bros., the shows have different contracts, production teams, and management policies.
Supergirl is on CBS and is filmed in Los Angeles, unlike
The Flash/Arrow/Legends of Tomorrow, which are on The CW and filmed in Vancouver, Canada. I guess budget also had to be considered, as they had to fly only Grant Gustin to L.A. to film his scenes. The fact that this crossover even happened was amazing in itself.