1 DM coin from the opening credits: The 1 DM coins shown in the opening credits with the (flashing) years 1948 and 1949 did not exist. The 1 DM coin was not introduced until 1950. From 1948 to 1950 there was only the 1 DM bill, which was valid until 1957.
The series name, Unsere wunderbaren Jahre, translates in English to "Our Wonderful Years."