Functional neurologic disorder (FND) is a “rule-in” diagnosis, characterized by positive examination signs or semiological features. Similar to other clinical diagnoses, providers should ideally see robustly present features, including if possible the identification of multiple features consistent with FND for the diagnosis to be made with a high degree of certainty. Diagnostic pitfalls need to be guarded against and vary depending on FND symptom subtype and the specific patient presentation. This perspective article aims to review pitfalls based on an FND symptom subtype, as well as discuss differential diagnostic considerations with respect to both neurologic and psychiatric entities.