[admantis]

SA-MP 0.3.8 features custom models, not cities from old GTA games. The cities are a consequence of being able to use custom models, which are taken from those games' model files. Since their engines are considerably old, you can expect some compatibility issues when attempting to port them into SA:MP, also exacerbated by the inherent limitations in SA:MP and the GTA:SA engine (i.e., water levels). The developers are aware of those problems, and they will be fixed in future revisions as it reads very explicitly in the 0.3.8 RC thread. For now, use manual fixes made by yourself.