When Dexter is on the boat and he gets a message from work, there is a pier visible in the shot, which would indicate he was close to shore. Then when he starts the engine and goes towards shore, they're in the middle of the sea.
The pier is close behind them, out of camera shot. They are going to the opposite shore, several miles away, giving the impression of being in the middle of the sea.
The pier is close behind them, out of camera shot. They are going to the opposite shore, several miles away, giving the impression of being in the middle of the sea.
While speaking to Deb near the scene of the burned car, Dexter has ash smudged on his forehead that disappears and reappears as the camera moves back and forth between her and him.
When Dexter and Hannah are on his boat, a range of hills can be seen in the background of one shot. No such hills exist in Miami.
Even if Isaak's highly proficient bodyguard Jurg was for some reason unaware that Hannah habitually poisons people, it is out of character for him to eat meals cooked unsupervised by a kidnapped hostage he was guarding.