Cody's position relative to the background when practicing his presentation on Saudi Arabia.
Doakes would not legally be allowed to interrogate a suspect who had obtained legal counsel without that suspect's lawyer present.
When Debra and Gabriel are in bed and Debra says she wants to break up with him, it is supposed to look like Debra has been listening to her iPod for a while, but when the scene starts the display on her iPod is illuminated and goes dark after a second or two. This means she just used the controls on her iPod.
When investigating the murder of the teenage girl, Doakes returns to the crime scene from the interview with her mother and briefs Dexter on what she had to say before inquiring about the blood evidence. The briefing is out of character. Dexter is not an investigator, just a forensic tech who does not need to know. Moreover, Doakes is suspicious of him and keeps antagonizing him.