Annie Parker's son, William, is born in November, 1973. From June 5, 1975 to January, 1978 in the film's timeline, the character is played by Benjamin James Stockham, who is credited as Young William (8). However, the character would have been between 1 and 4 during the dates listed in the movie. Benjamin Stockham looked young for his age, but not young enough to play a toddler! The movie jumps ahead five years later (presumably to 1983), with Ryan Wynott cast as Young William (12), but he wouldn't have been 12 yet. Even if we take the William character's ages - 8 and 12 - at face value, the math still doesn't add up with a five year time-jump. Ironically, Ryan Wynott is only a few months older than Benjamin Stockham despite being credited as four years older.
In a scene set in the late 70's/early 80's, Paul is seen wearing a vest made out of German Bundeswehr camouflage pattern "Flecktarn". This type of pattern was introduced in 1991.