These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Hilarious in Hindsight: Martin Sheen as foaming-mad mid-westerner President Stillson during the "the missiles are flying! Hallelujah! Hallelujah!" scene is especially funny due to his later role as the ideal Coastal Liberal president, President Bartlett, in The West Wing.
Christopher Walken as an English teacher who tells his class to read "The Legend of Sleepy Hollow" later plays the Headless Horseman in Sleepy Hollow.
Nightmare Fuel: Frank Dodd's final act is to lower himself onto his own open scissors - stabbing himself to death through the roof of his mouth. Johnny's vision of Stillson's eager reaction to giving the final launch order also qualifies.
Hilarious in Hindsight: In a Season 2 episode, Johnny is hit by a car while saving a child. He wakes up in the hospital and asks Bruce if it's 2009 (i.e., if he's been in a coma for ANOTHER six years.) Bruce deadpans "no... it's 2011." Johnny then asks if the Red Sox have won the World Series yet. We now know that in fact they have won it twice in the period Johnny's second coma would have covered, adding an added punch to this joke.