1989's Christmas Vacation is often regarded as one of the best holiday comedies to date, and arguably the strongest entry in the Vacation franchise. There's a reason for this, as it's chock-full of hilarious moments, quotable zingers, and plenty of holiday charm.

RELATED: National Lampoon's Christmas Vacation: 10 Facts Fans Didn't Know About The Holiday Movie

It's true that the Vacation films, and the National Lampoon brand at large is known for its more cartoony brand of zany comedy, satire, and slapstick. Still, Clark's escapades in arranging the perfect family Christmas bring some pretty implausible and odd moments. There are more than a few occasions where viewers are likely to chuckle at the sheer absurdity of certain aspects and events of this holiday comedy.

Clark Getting Stuck Under A Logging Truck

Christmas Vacation Opening Clark stuck under logging truck

Logic and physics can somewhat be disregarded when it comes to comedies, particularly those that have a goofier, slapstick bent. Still, it's tough to fathom anyone capable of swerving perfectly underneath the gap of a high-speed logging truck and live to tell the tale, as Clark does early in the film.

Not only this, but the naïve man doesn't even seem to be aware of what he's doing, despite pulling off this unlikely maneuver. How this occurrence ended up any way other than bringing total wreckage is anyone's guess.

How Eddie And Catherine Can Support All Their Kids

Ruby Sue holding a doll and talking to someone in National Lampoon's Christmas Vacation

Given the crude living conditions of Eddie and his family, it's clear that they're not too well-off financially. This is reaffirmed in a scene where Clark and Ellen are discussing their situation and the likelihood that they won't be able to give their kids gifts. It certainly makes sense, considering how many little ones these two have.

RELATED: 5 Ways A Christmas Story Is The Perfect Holiday Movie (& 5 It’s Christmas Vacation)

But even though they're obviously roughing it - it's surprising they're able to even support a single child, let alone several. After all, it's mentioned by Ellen that Eddie's been out of work for seven years. One can always hope that Dale will come through with his lucrative job barking for the yak woman at the carnival.

Lightning-Speed Sledding

Christmas Vacation Clark Sledding

Christmas Vacation shifts from zany comedy to full-blown Warner Brothers cartoon during the amusing sledding scene, which sees Clark zipping down a hill faster than a speeding bullet. It's hard to maintain that suspension of disbelief as we spend an extended period of time watching Clark fly a distance that seems to be miles.

What's even stranger about this scene - aside from the fact that he doesn't get killed - is that Eddie appears to react after he crashes so immensely far away.

It's a pretty wacky, over-the-top scene, even for Vacation standards.

Clark Cutting Down And Decorating A New Tree In Record Time

National Lampoon

Clark sure ends up putting a lot of hard work into assembling his perfect family Christmas celebration, despite everything falling apart. When Lewis accidentally ignites the Griswolds' huge Christmas tree, he opts for a quick replacement.

He seemingly quickly manages to cut down another tree near his house, drag it inside, and fully deck it out with lights and ornaments. This would appear to be within the course of just two or three hours, given that this all occurs on the same night and the family is present in the living room, hanging out the whole time.

Unfortunately for Clark though, he didn't take the time to notice the hostile squirrel residing in his new tree.

The Kids Are Clearly Younger Than Previous Vacation Films

Christmas Vacation Griswold Family getting Christmas Tree

It's fairly easy to see past the changing lineup of Griswold kids in the Vacation films, given how far apart they're spaced in terms of release dates. Regardless, it's pretty odd to see decidedly younger versions of Audrey and Russ this time around.

Russ in particular appears to be a few years younger than he was in years-old Vacation predecessors.

Highly Explosive Sewer Gas

Christmas Vacation Sewer Explosion Lewis

One cringes at the thought of Eddie's unsanitary waste disposal, which he deposits directly into the sewers of the Griswolds' block. Despite the lingering toxicity though, it's hard to imagine a scenario where dropping a match near it would ignite a huge explosion. Heck, it's so powerful that it blows back everyone standing in its vicinity and sends Lewis flying as if he stepped on a landmine.

RELATED: 10 Crazy Things About A Very Brady Christmas That Make No Sense

But hey, it certainly makes for an explosive way to end a film. We'll see ourselves out.

Clark Ordering His Pool Before Getting His Bonus

Christmas Vacation Clark Pool in office

Clark tends to fall on his face quite a bit and make questionable decisions, but really, that's part of his comedic charm. One prominent example is his financially questionable move to buy a presumably expensive swimming pool before getting his juicy bonus check.

Not only this, but he promises to pay for plane tickets for each member of his family as well - assuming there's enough left over. He didn't even have enough left in his account to cover the cost; a bold and potentially dangerous gamble, to say the least.

It makes sense on one level though, as fans of Vegas Vacation know of his tendency to gamble with big bucks.

How They Managed To Fit Their Tree In Their Living Room

Christmas Vacation Christmas Tree lot of sap

Russ said it best when he said "that thing wouldn't fit in our yard." And that hardly seems like an exaggeration, given how this massive tree utterly towers over the Griswolds. So either this Christmas tree has the power to shink, or Clark had to do some substantial trimming that would likely take hours.

Then there's the fact that they were apparently able to uproot this monstrosity without a saw. Obviously, we can see that this thing is a beast that takes up much of their living room, but it still appears quite a bit smaller than it looked when they first approached it.

How Eddie Is Able To Locate Clark's Boss

Christmas Vacation cousin Eddie kidnaps Clark's boss

Clark has a number of memorable quotes in this film, but one fan favorite is his rant after he learns that his bonus this year will be naught but a "jelly of the month" club subscription. During this episode of rage, he makes a tongue-in-cheek claim that his ideal gift would be to have his boss tied up with a big ribbon and brought to him. Eddie being Eddie, he interprets this literally, and takes off to nab him.

The question is - how exactly did he know where to find his boss? Clark does mention "Melody Lane," but surely even a community of large mansions has several homes he'd have to search.

The Unrealistic Labor And Hours Involved In Clark's Christmas Lights

Christmas Vacation Clark on Roof putting up lights

The Griswolds sure have an awe-inspiring display of Christmas lights, but it's hard to fathom the insane amount of time and effort such a project would take up.

It seems as though days elapse during most of this film; some of which Clark spends laboring on the roof. Still, individually stapling 250 strands of lights and managing a whopping 25,000 bulbs would ideally take weeks to knock out.

Next: 5 Ways The Original National Lampoon's Vacation Is The Better Movie (& 5 It's Christmas Vacation)