The authors discuss various problems that might occur in the process of integrating data for celestial bodies obtained from many sources. The data may be combined and the result of this combination is presented in a unified form which is the initial stage of creating celestial bodies’ maps especially those of the Solar system’s small ones. This process should be realized even before starting map compilation. Data integration is divided into three groups: spatial, geographic and thematic. A number of problems that we found out during analysis and compilation of such celestial bodies’ maps as asteroids 4 Vesta, 433 Eros, 101955 Bennu, comet nuclei 81P/Wilde and a satellite of Mars, Phobos, is described. As an example of mistakes it can be listed counting from a wrong prime meridian on the photomosaic and DEM, incorrect borders drawing for various relief features according to different sources, the problem of heights improper counting etc. It is supposed that such investigation will be useful for making maps of other celestial bodies as lots of these matters are expected to be more or less universal