Colonel von Strohm gets touchingly sad and upset when it appears that Hans has been abducted by the resistance. Also when he finds out that Hans has mistakenly been sent to England and will not come back.
Related to the scene above, an episode in one of the later seasons has René and Edith accidentally end up going to England, where they are reunited with Hans, who has became a naturalized English citizen. They are overjoyed at seeing him again and Hans treats them both like dear old friends.
The scene, where Monsieur Alphonse catches René and Mimi in flagrante, shows very moving chivalry from him. Even if he expresses his love by constantly grabbing Edith's bottom.
The Grand Finale, showing what became of the characters decades after the war. As we find out, the town erected a statue of Rene as thanks for his work with the Resistance.