"Boulder Dam" is actually Hoover Dam. Congress authorized the Boulder Canyon Dam Project in 1931 and, it being traditional to name big federal dam projects after the sitting President, named it Hoover Dam. Franklin D. Roosevelt defeated Herbert Hoover in 1932 but could not officially change the name set by Congress. Harold Ickes (FDR's Interior Secretary), however, issued a memo directing that his employees " . . . will refer to the dam as 'Boulder Dam' in this pamphlet as well as in correspondence and other references . . . ". In 1947, after Roosevelt and Ickes had died, Congress passed a resolution to "restore" the name of Hoover Dam. Until that time, however, all official, tourist and other promotional materials called it "Boulder Dam." The public's recognition with the old name was still apparent in the movie (released in 1950) through the script and the highway signage seen en route.
The movie was produced by Columbia Studios who owned Gilmore Stadium by this time. It tore down the stadium to build Columbia Broadcasting's Television City, the LA equivalent of New York's Radio City Hall, also owned by CBS at the time.
Mason goes to Gilmore Field for a ball game. It was the home of the Hollywood Stars, a Pacific Coast League team until 1957 when the Dodgers moved to LA.
Early in the movie, Mal Granger says, "I just wish I could lay my hands on Don Ameche for awhile, I'd teach him to invent the telephone." This is an obvious reference to actor Don Ameche, who played the title character in Liebe und Leben des Telefonbauers A. Bell (1939).