Experimental data from heavy-ion experiments at RHIC-BNL and LHC-CERN have been described very well by using relativistic fluid dynamics. Even data from p+A and p+p collisions show signs of collective behavior describable in the same manner. Nevertheless, small system sizes and large gradients hint to a failure of these theoretical methods. The range of applicability of fluid dynamics to small systems has to be checked. In this wrok we compare the results of calculations stemming from relativistic fluid dynamical simulations with solutions of the Boltzmann equation yielded by a transport theoretical approach for fixed initial setups. While there is an overall agreement of energy and particle density profiles, components of the shear stress tensor show more sensibility to details of the implementation. Quantities concerning properties of the medium after freezeout are even more critical. We also show that the region of agreement between fluid dynamics and kinetic transport theory extends into regions of Knudsen numbers and inverse Reynolds numbers where relativistic fluid dynamics is believed to fail. A critical view on the kind of observable is necessary.