There are the following limitations in the Rankine's Theory
(i) As the retaining walls are usually constructed of masonry or cement concrete, the back of the wall is never smooth, and hence friction develops.
(ii)due to assumption that wall back is smooth, the resultant pressure must act parallel to the surface but due to frictional forces, the active earth pressure gets inclined in the wall at an angle equal to angle of friction.
(iii) The wall back may not always be vertical. In practice a batter is given to the wall back.
(iv) The retained soil may not be always cohesion-less.
Reference: GK Publishers, GATE