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I've been having some trouble following the continuity of Dexter. If I'm not mistaken, then the first time they mentioned what year the show was in, was in Season 5, where Masuka said it was 2010. HOWEVER, the first episode took off right after Season 4, which supposedly took place in 2009, since that was the year it was aired.

Does this mean that, briefly, Dexter took place at least a year into the future, or was this just a writing mistake?