The Joy of Killing

Dexter repeats a line similar to his opening line from the original series while stalking someone in downtown Miami at night, "Tonight was the night", where in the original series, the first line is "Tonight is the night".

When disposing of Reed's body, Dexter had no gloves on, so his fingerprints would've been all over the plastic the body was wrapped in. This is a mistake an actual forensic employee would've never made, much less a serial killer, even in 1991.