[SPOILERS] James Gunn confirms that The Message in "Superman" is real

"How can someone not think it's real? I don't understand. In the test screenings people said, 'With AI, no one trusts anything.' So, okay, in the movie Mister Terrific says, 'I know those computer forensics guys, there is no way.' That's Mister Terrific, he's as smart as Lex Luthor. Then I have Mori, the Secretary of Defense, say, 'Think whatever you think about Luthor, but it's real.' And then the clincher is that Ghurkos and Lex are walking together and Ghurkos say, 'Ahh you doctored the message. This is great.' And Lex says, 'It's not doctored. It's real, and who thought it would be his own parents to bring him down?'"