The possibility of Supergirl heading to the Arroverse has been off and on again over the last couple of months. In December it looked like it wouldn’t happen, but then last month it was a possibility. Now it’s happening.
Today CBS announced a deal with The CW that will bring The Flash to Supergirl in the March 28th episode:
“We are so incredibly excited to announce something that we have dreamed of happening since we starting making Supergirl,â€ said The Flash and Supergirl Executive Producers Greg Berlanti and Andrew Kreisberg. â€œWe want to thank Grant Gustin for making the time to come visit (on top of his already immense workload) and all of the folks at CBS, The CW, Warner Bros. and DC for working this out.”
With characters like Red Tornado and Martian Manhunter in Supergirl, The Flash makes a lot more sense to crossover than Arrow.