Near the end of Fonzie's nightmare, the train that is heading for his stalled car on the tracks is an Amtrak train. Amtrak did not exist back in the mid-1960s, when this episode takes place (Amtrak was founded in 1971), and the engine is a typical Amtrak diesel locomotive of the time, which were not around until the late 1970s.
The wrecked car Fonzie purchases (and Nancy shows a keen interest in) is actually a 1953 Chevrolet Bel-Air convertible, not a 1955.
Tommy: Fonz, it's a 1955: your favorite year.
Fonzie: Was. Was. If we've learned nothing from history Tom, we've learned that people who live in the past are mostly... dead.
A popular song in 1965, the year in which this episode is set, was "Laurie (Strange Things Happen)" by Dickey Lee, in which the urban legend of a ghostly passenger is retold. Unlike Fonzie's almost-last-date, the girl in the song just wants a dance, a kiss and a hug, and a ride home. Like the girl's purse in the car at the end of the episode, the hero of the song finds the sweater he loaned Laurie on her gravestone. Like Fonzie's nostalgia for 1955, the song itself seems something of a throwback, especially with the British Invasion and Motown in full swing at the time.
Anson Williams and Ted McGinley do not appear in (at least) the syndicated version of this episode.
Kevin Rodney Sullivan is credited as "Kevin Sullivan."
The title of this episode comes from the Biblical quote, "The spirit indeed is willing, but the flesh is weak" from Matthew 26:41.