This movie is basically a modern It's a Mad, Mad, Mad, Mad World. In some ways it's better, while in some ways it's not.
First of all, the original had (supposedly) all the major comedians of its time in it. The most famous comedian in Rat Race was Whoopi Goldberg, who is way past her day. Cuba Gooding, Jr., could be argued to be more famous, but he's not usually thought of as a comedian. Yes, I know that Seth Green is the man, but he hasn't been in all that many famous movies. The only one I know he was in was the Austin Powers series.
The second thing that the original had on Rat Race was that the ending is way more realistic. In Rat Race, the guy with the money (John Cleese, who also can't be counted as famous because he wasn't a racer) gets screwed over for taking advantage of the racers, even though he was totally justified in doing so by their racing. In the original (I don't want to type all that out again, thought I suppose typing this is about as long as all the times I'd have to type It's a Mad, Mad, Mad, Mad World, oh well) the guy with the money actually dies, but you just know he's laughing his ass off in the afterlife when they lose all the money in the end.
Those two things are the weak points of Rat Race. The strong points are everything else.
Basically every comedy scene is hilarious. Unfortunately Rowan Atkinson, who is the man, is probably the lamest character because he's playing some lame Italian guy who isn't really all that funny. Well, sometimes he can be, and he's fun to immitate, but more often than not he's not. What I'm trying to say is that the scenes with the heart are funny at first, then get lame quickly.
This movie has several huge laugh-out-loud scenes. These often include low-brow humor, but hey, oh well, right? Anyway, Seth Green and his character's brother are great, especially in the scene where Seth Green is slamming into the cows, and the whole chicks in car/monster truck scene.
The scene that came most highly recommended was all the Hitler stuff, and holy crap, it was funny as hell! Between Hitler's car, his harmonica, his girlfriend's lipstick and shades, and of course the Hitler-talk bit, the whole thing was awesome.
Of course it helps that the helicopter chick is a total babe. I've never heard of her actress (tho I might have seen her in a movie and not known it) and I've also never heard of the guy she's with, but he's pretty cool too, but of course he doesn't have the Babe Factor (R) going for him.
Whoopi Goldberg and her character's daughter aren't funny usually, but you can't help but bust a gut laughing when the skeleton holding the I (heart) Squirrels bag falls on their windshield.
So if you want some cheap laughs, watch Rat Race, it rules.