Debriefing is considered, by many scholars, to be a fundamental part of learning through games and simulations. Despite its significance, there is a lack of research in the area of debriefing, which results in unaddressed factors that inhibit debriefing. Research in the field is complicated by many influencing factors varying from context to game, the purpose of the game, conditions and player specifics, facilitators etc. Insight in the role of these influencing factors can aid in understanding how debriefing can be optimized. In doing this research so far two viewpoints are relevant, the first is the design of debriefing and the second one is the actual execution of the debriefing. The aim of this study is to identify, on the basis of literature, the influence of factors and their interrelation, and subsequently, to categorize them based on expert opinions, so as to determine which pitfalls have the highest influence on inefficiency and ineffectiveness of debriefing. Based on 12 pitfalls identified in literature, and through the use of an online questionnaire, facilitation experts evaluated the extent to which these pitfalls occur due to the design or the execution of the debriefing, and the extent to which they are influenced by the rules of games and simulations. All 12 pitfalls seem to occur in practice, to some extent, due to both the design and the execution of the debriefing. Nevertheless, some pitfalls appear to be more influenced either by design or by execution. Moreover, the results on the extent to which the pitfalls are influenced by the rules of games and simulations are inconclusive, due to the contradiction between the answers on the pre-defined questions and the comments of the experts. A method for further extending the list of pitfalls and verifying the results, hence minimizing the threat to the internal validity of the study, is proposed, which includes a more extensive literature review, interviews, and case studies.