Beth has a new scar over her right forehead near the end of the episode after Dawn strikes her. However, Dawn clearly smacks the left side of Beth's face in the scene immediately prior.
Beth's ankle was supposedly so hurt that she needed to be carried. Now, she walks as if it was never injured in the first place.
When the officer confronts Beth about the scar on her left wrist, the scar looks fairly recent. In other scenes (such as when Noah is lowering her down the elevator shaft) her left wrist is clearly visible with no scar.
Even though she has absolutely no medical training whatsoever Beth somehow knows how to hook up and use an EKG. You can't just put the leads anywhere, there are three specific spots on the chest where the leads need to be placed for it to function correctly.