Why is it underrated?

Where to begin?

This is a cast of unparalleled semi-famous crappiness: Christine Ebersole (of the 1981-82 cast of SNL and My Girl 2), Jonathan Ward (the middle child from the first fanily on Charles in Charge) and Danny Cooksey (of the Dixie Carter Diff'rent Strokes cast and Salute Your Shorts on Nickelodeon). Cooksey is arguably the most "famous" name on this list, which boggles the mind on so many levels this computer is barely allowing the sentence to be written.

Also, rather than go through the normal capital raising process, Orion Pictures and the producers decided to just go ahead and sell the movie to the highest bidding advertiser. This resulted in some of the most ridiculous product placement you'll ever see. The movie is essentially a long running commercial. They constantly eat Skittles and drink Coca-Cola. Ebersole works at Sears (and some pretty weird hours also. If your boss wants you to work 3pm until close every night, he may not like you too much). The next door neighbor's oldest daughter (coincidentally about the same age as Ward) works at McDonald's, and Ronald McDonald played a large enough part in the movie to garner the 1988 Worst New Star Golden Raspberry award.

Speaking of McDonald's, it's the spot for the best scene in the film: a four and a half minute dance scene (which, oddly, features the only black people in the film), in which you can actually hear the director telling everyone what to do. There are no words for how surreal this spontaneous outburst of dance is. And the worst part is that the kid in the wheelchair can't even dance. The poor bastard has to sit there and watch everyone use their legs.

But here's the absolute cherry on top of the glorious crap sundae, and for those that like to go into a movie without knowing specifics this is a big spoiler alert: Instead of going back to their home planet at the end, ala E.T., they actually clothe themselves (presumably in some fine garb from Sears) and cut to a scene where the whole alien family become U.S. citizens. And with the NASA people looking on, as though they no longer gave a crap that this intelligent alien life form were living on our planet and they didn't want to do any more research. What the fuck? I mean, seriously, what the fuckety fuck fuck?

The movie is awesome in a Mystery Science Theater 3000 way. The plot holes are numerous. The dialogue is ridiculous. The acting is brutal. But the movie is bloody brilliant. It's everything that we love about movies that are so bad they're good.

We Won't Be Back!

There was a planned sequel to Mac and Me, such that the final scene of the movie is a freeze frame, with the words "We'll be back!" superimposed. But the movie got such lousy reviews and did so poorly at the box office, that the sequel was shelved.

I'm With Coco

There was a long running gag involving the movie on Late Night with Conan O'Brien. Whenever Paul Rudd would appear on the show to promote a film and Conan would introduce a clip, they'd cut to a clip of the kid in the wheelchair careening out of control down a hill.