The process matrix formalism was invented to describe multipartite quantum correlations, without the assumption of a well-defined causal order. Certain correlations contained within the formalism are incompatible with the assumption of a causal ordering of the events – these correlations violate causal inequalities. However, the formalism offers no clue as to how one might physically realise such acausal correlations. I will begin by explaining the process formalism, and I will then describe our attempt to understand these processes in a more physical way by making an explicit connection with certain aspects of the relativistic description of causality. We associate to each event a causal reference frame, which can be interpreted as an observer dependent time function, and relate the reference frames of different events via a consistency condition. I will then show how these ideas occur concretely by discussing some examples of interesting non-causal processes.