1x01 - Oliver appears in the pilot of The Flash
1X04 - Here goes Felicity
1x08/3x08 - A big 2-hours crossover event
TVD/TO writers should take notes from the Arrow/The Flash writers because that’s how a spin off is supposed to be. We know it’s difficult but you should give the fans crossovers.
Arrow/The Flash writers are doing a good damn job with that, they deserve an applause and a big THANK YOU for that.