!! FridgeBrilliance
* The incredibly-senile Aunt Bethany brings "presents" [[note]](actually, her cat and a Jell-O mold)[[/note]] wrapped in "HAPPY BIRTHDAY" paper. Christmas ''is'' Jesus' birthday.
* Could also count as FridgeHorror: Aunt Bethany asks Clark if his house is on fire, and Clark tiredly replies that it's just Christmas lights. It could be taken as a sign of her old age, but then I realized that the heat generated by the lights was actually causing the wood siding of the house to smolder, and she was smelling the smoke coming off of it!

!! FridgeLogic
* The two kids have their own rooms. Russ has a bunk bed. So why are the two kids sleeping in the guest room while one set of grandparents sleeps in Russ's room? Are the grandparents not getting along or something?
** It's mentioned by Clark and Ellen earlier that their parents DO NOT like each other, hence why each pair of grandparents has their own room. The first scene with the grandparents shows them arguing with each other.
*** I believe the previous Troper meant aren't each set of grandparents (Clark's parents Clark Sr. and Nora and Ellen's parents Art and Frances) getting along. If they were, it'd make more sense for Grandma and Grandpa Whichever to share the guest room (and guest bed), Grandpa and Grandma Whoever to share Audrey's room and have Russ and Audrey use Russ's bunk beds, rather than having Russ and Audrey share the bed in the guest room.
*** The Guest room bed is too small. Russell and Audrey are jammed next to each other (which, granted, was for that joke) and they're tinier, so there's no way Ellen's or Clark's parents would fit comfortably in there. Maybe they underestimated or always planned for Audrey to give up her bed...
** When Clark is trapped in the attic, he accidentally punches a hole through the floor into Russ's room. Why doesn't he just climb out through the hole he just made? It's not like he could make it much worse.
*** I have ALWAYS wondered this.
*** It is possible that he couldn't fit between the ceiling and the bed.
*** He made the hole, saw the projector while he was standing there, then decided to check out some old family movies before he left. Unless I'm forgetting the series of events, that seems most likely. Better answer: RuleOfFunny. Also explains why the bed was about 6 inches from the ceiling.
** How does Cousin Eddie know where to go in order to abduct Clark's boss? Clark simply mentions "Melody Lane" and "my boss," and Eddie comes back with the right guy. Even assuming that Melody Lane is a short street (which is a fair assumption, as it is made out to be an exclusive address), did Eddie go house to house? Does Eddie even know his kidnapping target's name? For that matter, the SWAT team zeroes in on Clark's house remarkably quickly, but admittedly Eddie's RV is an easily identified vehicle.
*** Clark mentioned his boss's full name (Frank Shirley) at the start of his now-famous rant. Eddie could've looked it up in a phone book or it's possible the Shirleys had their name on a mailbox or something. Shirley isn't ''that'' common a name, especially two on the same street.
*** Clark also mentions that Frank Shirley lives on "Melody Lane, with all the other rich people", making it out to be a very exclusive address. Cousin Eddie could easily have found him based on this information. Although, one has to wonder how he got past the community's security...
* When Clark and Rusty are putting up the Christmas lights, Clark says that he's "always wanted to do this", implying that they've never decorated the house before. So why are the lights all tangled up? Shouldn't they be new lights?
** It's not that he's never decorated the house, but that he's never decorated it to the extent he does in the movie.

!! FridgeHorror
* Clark's not going to be able to afford that pool he wanted. His Christmas lights consumed so much power that they caused a blackout across town and another generator needed to be turned on at the plant. You can even see the electric meter start rapidly spinning after the lights turn on the first time. When the electric bill comes in, [[YankTheDogsChain he can say goodbye to his Christmas bonus]].
** That's not taking into consideration all the damage sustained to the Griswolds' house and belongings throughout the movie; even if you don't adjust for inflation, they'd be looking at thousands of dollars' worth of repairs. And how much do you want to bet that the Chesters (the Griswolds' yuppie neighbors) will file a lawsuit against the family for all the property and emotional damage ''they'' suffered that holiday season?