At the beginning of the episode, Dexter and Deb are discussing whether to report for duty. However, from the count of bottles on the table, they have consumed too much alcohol to be considered fit for duty, especially on such a high-profile and dangerous case.
The goof items below may give away important plot points.
When Dexter is surprised after pulling out his syringe to use on Lila, he slips it into his back pocket to hide it. Later, Lila, who has taken Dexter's tools, opens the bag and finds all his killing equipment -including the syringe - neatly stored inside.
Lila finding a syringe in Dex's kit is no surprise, nor a continuity mistake, earlier in the episode when Dex checked his kit before heading to deal with Doakes there were clearly TWO syringes in the case. When Lila looked there was only one there since Dex had the other.
After Dexter injects Lila with an epidural, she says she can't feel her "legs or body"; Dexter tells her he opted for the epidural instead of the sedative to save time. Yet when Dexter lifts her up, she swings her arm behind his head to support herself in his arms. Obviously the epidural was intended to render her arms useless as well, so she could not fight back, a theory supported by the intentional lack of movement with her other arm.