I see two things: the most important is that I'm playing a lot with unreliable narrators and, although I know my readers know it, I don't know if they know which ones are the worst offenders. Sometimes the facts have been deformed by 2 or 3 successive persons before the character speaks in the comic.
Another, more anecdotic one is easter eggs and vague allusions. Most of them are 99% private jokes with myself, I just include stuff I like even if I know it's way too obscurely inserted or too far fetched to hope someone would find it. But, a few were found by readers anyway, and that was really, really nice!