When Spider-Man mentions Ben Reilly's being the real Parker and Peter being the clone sounds like a bad comic book plot, he's right - it comes straight out of a story in the comics that was not well-received. However, in the comics it was later revealed that this was false and Ben truly was the clone. This was most likely due to the poor reception. But in a way, Spider-Man is breaking the fourth wall with that comment.
Spider-Carnage's appearance shares similarities with Ben Reilly's second costume from the comics, most notably the larger spider logo on the chest, the "half boot" design, and the exterior web shooters.
Scarlet Spider's new name is taken from both his uncle and aunt. Ben's first name and May's maiden name.
Spider-Carnage unfairly hates Scarlet Spider. Even if he IS the clone, he was given Peter Parker's life by the original; he felt it unjust to struggle over it, and moved on.