In less than a week (prior episode), Darlene goes from have a major gash on her hairline (from being thrown into a bathtub), with significant blood dripping down her forehead, and side of her face, to zero evidence of this injury.
Dom is an FBI agent, and is on the run with Darlene from both the Dark Army and the FBI, yet she has her mobile phone with her, and it is switched on. Although Darlene also has a phone, it is probably understood that it is either not traceable to her, or traceable at all. However, it is safe to assume that the two made the necessary arrangements to ensure Dom's phone is also not traceable.