"Supposed to keep my return to @CW_TheFlash secret but never refuse a selfie request," Hamill wrote this morning in response to a fan's tweet. Does 'oops' count as an excuse?"
The photo, which first popped up on reddit, shows Hamill in costume, posing on a prison set with an unidentified "Flash" crew member. In the background you can see a wall covered with child-like drawings that depict The Flash meeting his end in a variety of grisly scenarios, suggesting The Trickster has become obsessed with the Scarlet Speedster since their last meeting.
Hamill, who first played The Trickster on the 1990 "Flash" series starring John Wesley Shipp, returned to the role in a March episode of The CW drama. Titled "Tricksters," the episode features Hamill as the imprisoned criminal mastermind James Jesse, who, united with a copycat killer using the name The Trickster, takes Barry Allen's father (Shipp) hostage.
There's no word yet as to when Hamill's new episode will air.
Starring Grant Gustin, "The Flash" airs Tuesdays at 8 p.m. ET/PT on The CW.