One of the biggest surprises coming out of Venom was just how much of the titular symbiote's classic origin made it into the movie. The trailers seemed to suggest that the creatures were man-made, inline with their scientific origin in the Ultimate comics universe, where the Venom suit was an attempt to cure cancer.
However, the very first scene of the film made it clear that the symbiotes are indeed extraterrestrial, showing a spaceship, sent to retrieve some samples of the alien beings, crash landing back on Earth. Though you never actually see where they're picked up from (apparently a comet), it's later confirmed by both Venom and Riot that there are millions of beings just like them floating around on a planet in space.
While the door is left open to see that in the flesh in future movies, the original draft of this film was initially set to travel to the planet of the symbiotes in the very first scene. Speaking to CinemaBlend, director Ruben Fleischer revealed that at one point the opening showed the Life Foundation landing on a planet (known as Klyntar in the comics) crawling with millions of the gooey aliens, but it was eventually cut in order to keep some sense of mystery about the creatures. He explained:
"The beginning of the movie was a hard one. Like, how much do we want to tell the backstory? There was a version [of the opening] where there was a planet crawling with tons of symbiotes that were collected and taken back to Earth by the Life Foundation. They had encountered them. But it kind of felt like, my instinct was it would be better to keep it more mysterious and just know that they've retrieved something from space. We don't know exactly by what means or how. Jenny [Slate]'s character later says they encountered it on a comet that was passing, and they retrieved these samples and brought it back to Earth. But yeah, I thought it was better just leave it a little bit mysterious, the backstory of the aliens."
One reason we're almost guaranteed to hear more about this planet in the next movie is the inclusion of Cletus Kasady, who turned up in Venom's first credit sequence. Though the scene was kept brief and was more fan service than anything else, an image taken from comicbook.com has revealed more about the enigmatic character, courtesy of Eddie Brock's own in-movie notes.
These shed a little bit of light on the killer's backstory, and indicate that Sony aren't pulling any punches when it comes to translating the fan favourite over to the big screen. Here, the notes explain that Cletus killed his own grandma by pushing her down a flight of stairs, went on a huge massacre in NYC which culminated in him killing 11 people, and then ended the night of anarchy by digging up his mother's grave.
From there it goes on to explore more of his childhood, revealing that he may have been responsible for setting his orphanage on fire, had a tendency to torture his dog with a drill and pushed a girl in front of a bus when she refused to go out with him. Charming.
Whether all this makes it into the sequel is unknown, but it more than sets a precedent for how unhinged the character is going to be - and that's before he's introduced to his symbiote powers.