Do you mean the odd dark spots on some of the meshes?
If so, try rebuilding the level's lighting (go to the top of the editor and click Build). Alternatively, click the arrow next to Build, which will allow you to build the lighting specifically as well as change the lightmass quality. If the problem persists you may also want to check that you have a lightmass importance volume around the level.
The other possibility I can think of is that the meshes have problematic lightmaps, but that's probably unlikely to be the issue in the default third person map! If you are ever having similar problems in the future with imported meshes though, remember to check their lightmaps, especially for overlapping UVs.
Good luck! -Noah