The clinic to which Benedict sends Jonathan to treat his polio was run by Sister Elisabeth Kenny, founded in 1932 in Townsville Queenland, over 2000km away from Sydney, which is where the last ticket went to that Slade gave Jonathan as a Christmas gift.
It took five hours to apply the old age make-up for Henry Winkler. Moreover, said old age make-up took about an hour to remove.
Based on Slade being a pre-teen in the earliest flashbacks, said to be "40 years ago," the elderly Slade would only be in his late 40s or early 50s, seemingly too young to be as wrinkled and white-haired as he appears. This is in keeping with Dickens' original version of Scrooge, who, while generally depicted as withered and decrepit, was seemingly meant to not yet be in his 60s.
One of the places they go to repossess the furniture has a copy of A Christmas Carol on which this is based.
This movie was made for television.