During his panel today at Wizard World Chicago, Arrow star Stephen Amell told his audience about working with Constantine star Matt Ryan, who will cross over into Arrow this season following the cancellation of his own DC Comics series.

"I've been filming scenes all week long with Matt Ryan," Amell said during the panel. "He is such a treat. And a trip. He's always saying his lines -- and he's getting ready to go on Broadway right now with Kiera Knightley, so he's always saying those lines, too. I can't tell if he's having a conversation with me, or preparing. And sometimes I chime in, he'll be like 'I wasn't talking to you, mate.'"

You can see Amell describe the experience below.