The analysis of slope stability problems may often require considerable attention for 3D effects, such as the curvature of the slope, the contribution of the piles and the local loading of the slope by the structures. In this paper, the effect of each contributing factor on the global stability of a 3D slope was carefully and comprehensively investigated by making use of a field case. However, the conclusions drawn from these analyses are not specific to a single case study. Using a couple of hundred analyses that were run within the context of this paper, some guidelines were provided and the influence of each factor on the factor of safety was clearly stated. The results indicated that, the influence of plan curvature can be defined with a unique relationship based on the factor of safety of the slope which is itself directly proportional to the radius of curvature of the slope. Considering the case of local loading on top of the slope, the loading distance and the size of the numerical domain on the shape of the failure mechanism were investigated in this paper and these effects could be demonstrated in the light of the results. Moreover, the influence of piles on slope stability was studied not only for the common "no surcharge case", but also for different loading conditions in order to optimize the effective pile location. The effect of the pile cross-sectional shape was also discussed in order to optimize the CPU time. Thus, the results of this study are intended to reveal some key issues and bring insight into the design processes.