Finite element (FE) models of the human brain are often validated against cadaver brain deformation experiments and are then used to predict brain injury based on strain metrics. The current study evaluates three factors hypothesized to influence FE model brain displacements:​ the mass of tracking targets implanted in cadaver brains, variations in brain size/shape, and variations in Neutral Density Target (NDT) locations. The first two factors were also evaluated for their effect on brain strains. Baseline simulations of five experimental impacts were conducted with the Simulated Injury Monitor (SIMon) Finite Element Head Model (FEHM). Next, independent model variations were made and the impact kinematics were again applied. Point masses were added at NDT locations, the model was scaled to various sizes/shapes, and the NDT locations were offset in three directions. Modified model results were compared to the baseline simulations. Adding point masses had almost no effect on brain displacement metrics or brain strains, while model scaling influenced both. Changing the NDT locations had the largest effect on brain displacement histories. These results indicate that size, shape and NDT location differences between experimental specimens and FE models must be accounted for in brain model validation studies.