Plot hole: Although this film is a virtual jigsaw puzzle of flashbacks, the dynamic between Dan, Laurie and Rorschach pretty much defines the movie's continuity in the present. However, when Rorschach is framed for murder and arrested, he goes directly to a maximum-security prison, apparently without trial, conviction or sentencing (all of which would require months of due-process, at least). Even if this lapse of time is some sort of artistic device to rapidly advance Rorschach's story, there is no corresponding lapse of months in the relationship between Dan and Laurie, which runs parallel with Rorschach's story. Either there is no due process for Rorschach in this story, or there is a glaring plot hole.
Revealing mistake: When Veidt and his cat Bubastis is walking over the bodies of the scientists after he poisons them, you only see Veidt's reflection and not Bubastis' in the energy panels on the walls as he walks towards and up the stairs.
Suggested correction: Rorschach was a famous and dangerous outlaw. We are talking about an alternate 80's here with Nixon as president and a nation-wide ban on masks (the Keene Act). Rorschach probably faced the death penalty for his long list of crimes, besides the murder he was finally captured for (not to mention to handful of cops he seriously injured whilst trying to evade capture). I don't think it's strange that his trial was quick or not fully by the book. They made sure he was locked away fast and quietly. The justice system probably works a lot faster in a world of masked vigilantes.
lionhead
Yes, Rorschach was a vigilante; but, before masked superheroes were outlawed, Rorschach was also responsible for sending dozens (if not scores) of far worse criminals to prison, thus benefitting society. This much is stated in the film. His contributions to justice would certainly carry weight, and testimony in his favor would have to be considered in any legal proceedings against him. Also, after his capture, authorities were still trying to assess his mental state, which implies that some sort of due-process was still in place. Rorschach should have received a months-long trial, at the very least.
Charles Austin Miller
To be fair, the original, Hugo Award-winning "Watchmen" graphic novel makes the same continuity leap when it comes to Rorschach's fate. Rorschach keeps a secret diary that dates everything, but it egregiously skips over his trial and sentencing, even though the relationship between Dan and Laurie remains consistent. So, we can say that the movie is faithful to the novel, but the novel itself is flawed with a gaping plot hole.
Charles Austin Miller
The cops of that city don't care about his past deeds, which includes dropping the body of a criminal in front of the police station with the message "Never." They don't like him. Not even his colleagues liked him. That was a long time ago too, he's been the sole masked vigilante for a long time and I bet the cops just started disliking him more and more for his antics. Thus, a quick trial.
lionhead