Andrew Kreisberg mentions that while Arrow uses far less CGI than The Flash and Supergirl, digital effects are used by the Green Arrow.
That’s just the subtle stuff you don’t really pay attention to, let’s not forget the spaceships, entire worlds, meta battles, and telepathic gorillas we’ve seen in the past year on both shows.
When you think of it like that, maybe blowing up an island (which was likely CGI) isn’t that costly in comparison.
Did you just assume Stephen Amell was also a master archer in addition to a champion of the salmon ladder?