A passive multiple trailer system provides various practical advantages in order to develop multi-functional service robots. So far, we have proposed kinematic design of passive trailers, and backward motion control schemes in our prior work. In this paper, we propose two significant considerations based on practical experiences on backward control of multi-trailer system. The first issue is an analysis on the effect of joint errors. Joint errors include joint angle sensing errors and backlashes at the joints. Due to the joint error, the trajectory shows an offset distance from a desired reference path. A second issue is a slip detection based on a simplified dynamic model of the trailer system. The trailer system is designed based on the kinematic constraints, which imply rolling without slipping at wheels. We discuss how a practical trailer system can be controlled without violating kinematic constraints. Finally, we show the analogies and relationships between the off-hooked trailer and the previously proposed three point trailer.