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.
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: While Dexter's searching for info on Travis Marshall on his laptop, he opens the DMV Records window with an image of Marshall's driver license, and in the closeup at the bottom of the license it reads "Operation of a motor vehicle constitutes consent to any sobiety test required by law," with the word "sobriety" missing the letter "r." Additionally, under the image of the license it reads "Issued: 10-12-2006", but on the actual license image it reads, "DOB: 11-24-1977, Issued: 09-23-1990, Expires: 09-23-2012." So that means Marshall was not even 13 yrs old when he got his license, and the license won't expire for 22 years. Also, when Brother Sam knocks on the door Dexter clicks back onto the MOA website, and if you care to pause the screen note the word "Exibit" is missing the letter "h."