That's a new look Corky's got there.
Yeah, no wonder Superman didn't recognize him. This must be a future mutated grenade....although that third eye is kinda Hinduish. But perhaps the story was compromised by undercover operatives from Bill Craig's group insinuating some sort of Molinistic "middle-knowledge" by it.
Methinks in Corky's time-traveling escapades he must have encountered an evil scientist, a madman, if you will, who changed Corky into this monstrosity. The crazed scientist, under the banner of Lexcorp, altered Corky's mind to battle Superman.But during battle, Corky's personality surfaced and Superman recognized his friend by looking into the "window of his soul".
This is what happens when grenades blow up.