Continuity mistake: Halfway into the film, Shakespeare is holding Viola's face placing his hands around her jaw, looking closely at her. When the angle is behind Viola, we see that her hair gets caught around his left hand's fingers. The angle changes to a wider side angle and his hand has no hair around, even though he hasn't moved it at all.
Continuity mistake: In the tavern scene, when Shakespeare and Marlowe are speaking, there is a bartender. In the shot in which Marlowe says, "His best friend is killed in a duel by Ethel's brother or something. His name is Mercutio", the bartender starts looking at Marlowe, and by the end, he turns his eyes towards Shakespeare. In the next shot, when Shakespeare says, "Mercutio... good name", the bartender's face has immediately turned toward Marlowe, without any time to do so.
Answer: In real life, Viola, of course, would be recognized as a female in disguise. However, in literature, film, opera, etc, it often is necessary to employ what is known as a "suspension of disbelief." That is, the author expects the reader or audience to know something is impossible, unlikely, or completely unreal, but they have to accept a certain premise in order to allow the plot to unfold. We go along with the idea that no one realizes Viola is actually a woman, so that we can enjoy the overall story.
raywest ★