Prior literature reviews on combining Industry 4.0 (I4.0) and Lean Production (LP) in production has often described the paradigms as “supportive”, where either “I4.0 supports LP” or “LP supports I4.0”. In this systematic review of 50 studies from this growing area of research, we find evidence of cases where combinations have not been “supportive”. We also find evidence of causal interactions that cannot be subordinated “I4.0 supports LP” nor “LP supports I4.0”, and that plainly go beyond those two categories. Additionally, we find that several studies evaluate the merits of I4.0- and LP combinations without looking at their effects on results in production, which substantially reduces the use of these evaluations to production managers. We encourage future studies to use nomenclature that does not unnecessarily limit the overall perception of the properties of I4.0- and LP combinations, to evaluate the merits of such combinations more in line with the requirements of production managers, and to be more cautious when concluding on causal interactions between I4.0 and LP.