This is the first film in the series not to be based on anything actually written by Lucy Maud Montgomery. But it is very loosely based on the 8th Anne novel "Rilla of Ingleside", actually written about Anne and Gilbert's 7th and youngest child, Rilla and her time during WWI.
The plot of this film bears little resemblance to the storylines of any of the "Anne" source books because of legal disputes that were at the time ongoing between Kevin Sullivan and the heirs of Anne author Lucy Maud Montgomery. Ultimately, Canadian courts agreed with the heirs that Sullivan had withheld from the heirs contractually promised profits from the first two films in the series (Anne of Green Gables (1985) and Anne of Avonlea (1987)), and the courts also found groundless Sullivan's $55-million suit against the heirs.
When Anne and Gil return to Prince Edward Island, they tell Dianna and Fred that they are going to move to Glen St. Mary. In the books this is where they move to after they get married and where they live for the books Anne's house of dreams, Anne of Ingleside, Rainbow Valley and Rilla of Ingleside.
When Anne and Gil reunite, we see that Gil is a lot older than the last time we saw him. His hair is much more gray and his face has aged. However, in the next scene he is no longer aged and his hair is no longer gray. This can be explained in the commentary as the director and producer state that they shot the scene several months prior to the scene before.
(at around 54 mins) When Gil is discussing whether or not the pregnant lady should be admitted, Dr. Powell grabs Gil's arm to further discuss the schedule. When it goes back to that shot, Dr. Powell is holding Gil's jacket.
Gilbert Blythe: You know, every day I would pick a different memory of you and play it over and over and over again in my mind, until every hair, every freckle, every part of you was exactly as I remembered.