Imagining hypothetical events often entails the construction of a detailed mental simulation. Despite recent advances, debate still surrounds the fundamental constructive process underpinning simulations supported by the hippocampus. Palombo et al. (2016) report findings that suggest that scene construction drives hippocampal engagement during imagination. However, they fail to consider the findings of a previous study using an extremely similar manipulation that generated similar hippocampal findings, but was interpreted in terms of event specificity and relational processing (Addis et al. 2011). While we applaud the general approach taken by Palombo et al. in attempting to distinguish components of mental simulation, a comparison of these 2 papers has brought into sharp relief how the lack of a common theoretical framework can result in significant interpretative ambiguities. In this commentary, we attempt to identify and clarify these as yet unresolved conceptual issues that will require empirical and theoretical attention in future research.