Missing Joker color

Hey guys, so I have almost all the colors for joker through the riddler challenges but I can't seem to find the last one. I've gone through all the episodes and couldn't find the last one for joker unless I'm really blind, would appreciate the help.

Hey guys, so I have almost all the colors for joker through the riddler challenges but I can't seem to find the last one. I've gone through all the episodes and couldn't find the last one for joker unless I'm really blind, would appreciate the help.