@bigladiesman  
I still love the utterly deadpan “Holy Shyayt” that comes out of Burt Reynolds’ mouth when he first sees him.

 
The best character of the movie is Van Helsing. Jack Elam always gets me.

@Pulse Wave  
Well… according to the original artist at the link, the lineup is:
 
Pinkie - Victor/Captain Chaos (Dom DeLuise)  
Fleur - Pamela (Farrah Fawcett)  
Dash - J.J. (Burt Reynolds)  
Derpy - Dr. Van Helsing (Jack Elam)  
Berry Punch - Jamie (Dean Martin)  
Trixie - Morris (Sammy Davis Jr.)  
Octavia - Marcie (Adrienne Barbeau)  
Rarity - Jill (Tara Buckman)  
Luna - Sheik Abdul ben Falafel (Jamie Farr)
 
EDIT: Heck with it, in case someone has a fanfic idea ;) here’s some more of the cast:
 
Hawaiian Tropic car drivers: Applejack and Big Mac (Terry Bradshaw and Mel Tillis)  
Mad Dog and redneck (drives GMC pickup): Vinyl Scratch and Braeburn  
Seymour - Pony Joe (Roger Moore) hint hint  
Jackie Chan and Michael Hui - Not sure (maybe Twilight and Lyra)
 
So you were 100% right about which pony becomes Seymour Goldfarb, Jr.

I have a question: Trixie aside, would any of the show’s other villains be among the drivers?
 
And am I alone I seeing Applebloom and Babs as those two guys with the orangutan “driver” in the second movie?
 
“Don’t even TRY ta explain ta me how we’re related again!”

This cast is next to perfect. Especially Berry Punch as that drunkard Blake, played by that drunkard Dean Martin.
 
Although I would have made Haakim the Sheik. And where’s Pony Joe as Seymour Goldfarb, Jr.?

They came from Canterlot. So the Wheel’s on the wrong side, so it’s actually Trixie that’s driving.

LOL Berry Punch driving…

@Ardashir  
I know. The more I thought about it the more the dogs seemed to be a better choice. :P

@lonewolf  
I suggested that myself at the link, but the artist’s decision was for them to be the Changelings due to how they got curbstomped in the wedding episode.

@Ardashir  
I think the Diamond Dogs would fit better.

Let me guess, the biker gang turns out to be the Changelings?

Oh this is great. Pity we didn’t get to see the scene where Pinkie introduces the “doctor” to Dash.
 
Pinkie: “I found us a doctor, Dashie!” Opens doors to reveal a crazed looking Derpy/Muffins.
 
Dash: (Totally deadpan): “Holy shyayt.”

The casting is PERFECT.

@Bexar Bandito  
Ball. Cannonball.

Damn, Rarity has the quite the leg power, because the Countach’s clutch is extremely heavy.

At the end, Pinkie’s going to rename herself Captain U.S.E.*
 
*(United States of Equestria!)

@Ichijoe  
Now that takes me back.

what do you say when there are no words?

“Trixie and Berry want to bless us. I’m pulling over.”
 
“Re-elect Princess ‘Kill a Commie’ Celestia: Faust, magic, and guts keep us safe from Discord supporting nuts”

@Jim Prower  
That was Cannonball Run II…and weirdly it didn’t total the Porsche.

That movie was an example of how a film can be absolutely awful yet a ageless classic at the same time.

All I know is that Bigfoot 3 crushed a 928 in one film.

Knew what it was right away.
 
Friggin’ love these movies.

Only us really old farts are gonna get this… I think. But, damn I must have been like Nine at the time when this cane out.