As the episode starts, and Al is making initial contact with Sam, Al claims to have had a '48 Harley Knucklehead. Harley stopped making the "Knucklehead" engine in 1947 and began making the Panhead engine in 1948 to take its place.
When Sam crashes the bike near the beginning of the episode, Al joins him at the side of the road. In these shots Al's clothes are clearly blowing in the strong coastal wind. As a hologram, people and other objects pass right through him; the wind should not be able to affect his clothing.
Although this episode takes place in 1958, the books in Ernie's spare room include "Basketball My Way" (1973) by Bill Libby and Jerry West, "Encyclopedia of Grafitti" (1974) by Robert Reisner, "Sam 7" (1977) by Richard Cox, "Overload" (1979) by Arthur Hailey and "The Medusa Complex" (1982) by Marvin H. Albert.