Steven Spielberg is a master cinematic storyteller, and he did a remarkable job with Schindler’s List. In movies of this caliber, we often see symbols that we may not recognize for their symbolic value. That doesn’t mean that they don’t have an effect on our perception.
Several times in the film, Schindler offers Stern a drink. Stern refuses because he sees Schindler as a Nazi that he doesn’t particularly want to associate with. But late in the movie, Stern himself suggests they have a drink together. At this point he respects what Schindler has done for his workers. The drink symbolizes the change in their relationship and the fact that they have become partners of a sort.
There is also a scene in which Goeth shoots a houseboy who fails to clean his bathtub well enough. The bathtub symbolizes Goeth’s filth—like Goeth, the tub is too dirty to be redeemed. No human can redeem the tub or Goeth, not even Schindler, who has been trying to change Goeth into a gentler man.