9 Huge Mistakes In The Harry Potter Books You Didn't Even Notice

5. Sirius Black's Memory Is Seriously Clouded By His Time In Prison

Even though it's a small detail, this is another example of how certain things can simply get away from writers when contrasted against the grand scheme of things. In Harry Potter And The Prisoner Of Azkaban, Sirius Black claims that Voldemort has been hiding for fifteen years.

Fifteen years is a nice, even-sounding amount of time, but unfortunately it's rather inaccurate, and even more unfortunately, Sirius should have been well aware of the actual amount of time. It's clearly known that Voldemort went into hiding as soon as his soul was torn from his body following his encounter with Harry Potter. This is basically the same time that Sirius was wrongfully imprisoned for supposedly giving the Potters over to Voldemort, so he'd clearly be aware of when that was.

When talking to Harry, then, Voldemort has only been hiding for twelve years, not fifteen. Three years is a pretty significant gap... and if he was rounding the number for simplicity, he would have been more accurate to say ten, not fifteen.