As mixed reality storytelling becomes more popular we are beginning to see examples of where it can go wrong, by causing harm to those that directly participate, or offence to those indirectly affected. Without an ethical framework to inform design, mixed reality storytelling could have the same sorts of unintended consequences as other digital technologies (for example, social media that has led to mass surveillance and problems with anti-social behaviour). But what might these be? In this paper we explore a range of ethical issues that could affect mixed reality storytelling technologies in order to illustrate the complexity that awaits as they become more popular. We describe ethical responsibilities under two broad themes. The first is a responsibility to the place, in terms of avoiding physical trespass, respecting cultural norms of behaviour, control over virtual graffiti, consideration of names, and awareness of the values embedded in narratives. The second is a responsibility to the person, in terms of safe passage, expectations of accuracy, respect for social and psychological norms, and obtaining wide consent. In both cases there are unresolved legal questions about the duty of care that designers have for their participants, and cultural questions around balancing the competing claim rights of stakeholders with the liberty rights of artists, writers, and designers.