While at the unemployment office, Rob mentions that his middle name is Simpson.
The title comes from the rallying cry from the era of the Oregon Territory dispute in the mid 19th century, for the U.S. claim of territory further into Canada. "54 - 40 or Fight!" refers to the latitude in question. The claim was later settled along the 49th latitude, the U.S. / Canadian border.
Guest star Reta Shaw (Mrs. McCracken at the unemployment office) was also in Mary Poppins with Dick Van Dyke.