Willa Holland and Katrina Law appeared at the recent MCM London Comic-Con where they confirmed character deaths on Arrow are a result of the DC movies.
Holland and Law confirmed the Suicide Squad character deaths in Arrow were a result of the movie, and it's heavily speculated the same applies to the recent death of Black Canary in the series as well. It's also been said Atom was used instead of Blue Beetle because of potential movie plans.
Holland and Law also make comments that they think both Stephen Amell and Grant Gustin would have killed it in the DC movie universe if allowed to play their respective characters of Green Arrow and The Flash.
Watch the video below for more.
When DC found out they were going to be doing their own movie we had to axe all of the characters before we even got to show them.
It was annoying at first and then when Stephen found out there was going to be a Justice League movie it only seemed, rightly so, he would be playing Green Arrow on it as well as Grant playing the Flash. It just seemed like the right normal answer.
Once they said no, you can't really fight against them for it, because they are the people that gave us a job in the first place.
You just have to sit there on your hands, like okay, I get it!"