Edward Snowden made a surprise appearance at the secret screening of Oliver Stone's film, "Snowden," at the San Diego Comic-Con.

The screening was the film's first public screening, albeit being attended by a handful of journalists whom were invited to preview the film. Towards the end of the film, Snowden made an unannounced appearance in the form of a video call, which was projected on a large span of wall, The Verge reported.

Stone, the film's director, was also in attendance of the premiere, as well as Joseph Gordon-Levitt, whom of which played Snowden in the film; and Shailene Woodley, whom played Snowden's longtime girlfriend.

The Hollywood actors presence were overshadowed by the unexpected appearance of Snowden, although he was absent physically. The WikiLeaks whistleblower's manner of appearance didn't seem to degrade his presence, as the entire audience turned focus onto him.

Snowden was prompted to give his opinion about the film, which was about his time with the NSA up to the point of controversy which ultimately led to his exile. The whistleblower said that as a person who built his career in line of privacy and secrecy, he didn't necessarily look forward to having a movie made to depict him, as well as his life, according to Reuters.

It has been revealed at the secret screening that Snowden himself contributed to the film more than anybody expected. It was a given that he was in support during the film's development, but everyone in attendance were left having one particular scene stuck to them.

In one particular scene, it was revealed that Snowden had a cameo in the film; and a powerful one at that. The exiled whistleblower actually portrayed himself in one scene, which reportedly took nine takes to film.

"Snowden"is set to roll out to theaters in September of this year. The film follows Snowden's life from his discovery of the NSA's mass surveillance, including American citizens, eventually resulting in the U.S. government filing espionage charges against him.