When the police are sent back to the scrap yard to look for more evidence, the hubcap is where it was originally, although prior to that (when Dexter got in the trunk to see what the kid would have seen), Dexter kicked the hubcap away from its original location.
The nipples of the dead woman in the trailer are erect; this would not be the case if she were dead.
Children's protective services quickly place the Cuban refugee boy with his just-located uncle. Normally, CPS would require foster certification, even of a family member, and while it could expedite this process, it wouldn't occur as quickly as depicted here.
At around 24 mins when the scalpel is cutting Dexter's cheek, the blood tube along the scalpel is visible under it for a short moment, revealing the mechanical method of the effect of leaving blood with a cut.
Every item that Dexter throws into the ocean, large or small, makes the exact same splashing sound, indicating a prerecorded sound being used again and again.
When Dexter and Masuka are gathering forensics from Castillo's corpse, her neck can be seen moving from either swallowing or her pulse while Dexter is recording the needle mark.
The Cuban boy Laguerta hugs near the old Mercedes is looking at the panning camera from under her shoulder.
During the flashback of Debra firing her dad's gun, the dry, brown hillside across the water is completely out of place for South Florida.
When Sgt. Batista introduces Debra and Sgt. Doakes to Mariel, he refers to Debra as "Detective" when she has yet to attain that title. Her correct title is "Officer" Morgan.
The birthday party sign which Rita makes for her daughter reads "Happy Birtday" (missing the "h").
The little boy and the woman called in because of the phone number found are both identified as Cuban. However, they both speak with strong Mexican accent.