Other mistake: When Dexter is running Matt Chambers' fingerprint though his computer, he brings up four newspaper articles where the names Matt Brewster and Matt Rasmussen are used. In the final article, the headline reads "Matt Rasmussen of South Boston arrested", but the body of the article uses the name Matt Brewster exclusively. Other than the first few words, the text of the final article is identical to that of the previous one.
Other mistake: The marriage certificate for Rita's first marriage shows her date of birth as 04-19-1989 and Dexter states she married at 16. The marriage date is 08-16-1989, when she would have been 4 months old. She also would only be 17 at the start of the series (2006) if she was born in 1989.