The 100th episode is quite a milestone for any network show, signifying (at least) five years on air.
We had to take them from the old episodes and roto them out and then put them into [the 100th episode].”
After being abducted by Dominators at the end of The Flash‘s Invasion! episode, Arrow picks up with our heroes being brainwashed by the mysterious and hostile aliens.
The [visual effects team] did an amazing job, particularly with Colin and with Colton because we couldn’t re-shoot them.