Even taken together, the charges didn't seem to amount to that big a deal — just a matter of quoting a few factual statements and a Wikipedia passage without attributing them. But as Rand Paul discovered, the word "plagiarism" can still rouse people to steaming indignation. Samuel Johnson called plagiarism the most reproachful of literary crimes, and the word itself began as the name of a real crime. In Roman law, a plagiarius was someone who abducted a child or a slave — it's from "plaga," the Latin word for a net or a snare.
[This piece contains some plot details about About Time, but nothing major that isn't revealed in the film's marketing.]
Movies are the closest thing we have to time travel, so it's no wonder — or rather, it's a rich and enduring wonder — that so many memorable films have made it their subject. Actually, let's strike that. Few if any of those films are actually about time travel. Most films that involve it use it as a means of discussing something else.