Continuity mistake: Guy of Gisbourne says to Robin Hood that he should lay down his weapons. Robin Hood throws his bow and sword on to the ground. He then gets thrown down the cliff, into the river. A few minutes later, when we get focused on him again, we see that the bow is lying in the river with him. (00:06:05 - 00:10:55)
Character mistake: Stella goes to the hospital to inform her daughter Sam about Hope dying. During the conversation, Stella calls her daughter Samantha and later on calls her Sarah twice.