This report has two main goals. First, it numerically investigates three velocity-pressure reduced order models (ROMs) for incompressible flows. The proper orthogonal decomposition (POD) is used to generate the modes. One method computes the ROM pressure solely based on the velocity POD modes, whereas the other two ROMs use pressure modes as well. To the best of the authors' knowledge, one of the latter methods is novel. The second goal is to numerically investigate the impact of the snapshot accuracy on the results of the ROMs. Numerical studies are performed on a two-dimensional laminar flow past a circular obstacle. Comparing the results of the ROMs and of the simulations for computing the snapshots, it turns out that the latter results are generally well reproduced by the ROMs. This observation is made for snapshots of different accuracy. Both in terms of reproducing the results of the underlying simulations for obtaining the snapshots and of efficiency, the two ROMs that utilize pressure modes are superior to the ROM that uses only velocity modes.