The Stranger (Jonas) carries a necklace with a medal of Saint Christopher. Legend says that he carried a child, who was unknown to him, across a river before the child revealed himself as Christ. Therefore, he is the patron saint of travelers.
In the original German language version when the orderly unlocks the door to Ulrich's room he says " alles klar, Kommissar?" This is from a poplar German 80s song Der Kommissar by Falco and later translated into the English version by After the Fire.