Factual error: When Elektra closes her cell phone on McCabe, a dial tone can be heard. Cell phones don't have dial tones. Even if they did, Elektra hung up, so nothing would be heard.
Revealing mistake: When Elektra attempts to resurrect dead Abby, you can see Abby's chest rising and falling.
Continuity mistake: When DeMarco lifts his glass to look at Elektra you can see there's no meniscus where the liquid hits the glass. When it cuts to a close-up of the glass there now is. (00:05:55)
Continuity mistake: In the last fight seen next to the well, the well is close behind Elektra, but when she gets hit backwards the camera cuts to a side view and the well and Electra are a lot farther apart.
Revealing mistake: When the young girl "dies", you can still see her blink and breathe.
Plot hole: Elektra was said to have trained her whole life yet here she seems to need more, as if she's new to martial arts.
Suggested correction: Just because she's been training her whole life doesn't mean that there's not more to learn. Even experts continue to train in order to learn new things.