The strangest part of that film is the ten minute long uncredited appearance of Robin Williams.
I thought it was neat that they got the actors who played Spanky and Alfalfa to appear in thee Our Gang movie.
Just about every well known actor from the '30’s appeared in Won Ton Ton. I had to watch it twice to catch everybody.
His mother was the casting director for that film.
I was watching a Mr. Ed rerun in which Irene Ryan appeared. Her character wasn’t named, but she looked and spoke like Granny from The Beverly Hillbillies and even made reference to being a doctor.
I don’t suppose any of the wall-climb cameos on Batman count, do they?
Also a bit part in the first Austin Powers film. " I brought you your orange sher-bert."
Pretty much any of the foreign work of Spanish actor, writer, producer and most definitely non-heartthrob Santiago Segura. I swear his friends cast him specifically so they’ll be able to get that moment where the crowd in Spanish theaters goes “no way! No fucking way!” and to have everybody stay until the closing credits finish rolling by to verify that yes way, that pizza delivery guy / dude standing at traffic light / taco vendor was him.
Vague hyperlinks are so annoying, SDMB, especially on a smartphone.
While it’s long by cameo standards, I’m picking James Brown in Rocky IV for sheer WTF factor. So James Brown exists in the Rocky universe? What is he doing there? There’s no song and dance in boxing. The whole mess is indicative of how bloated and off the rails the franchise had become since its nearly perfect first film.
Sorry, but saying who it is would ruin the entire joke of that scene. But here you go: it’s from Wayne’s World 2 where Mike Myers complains about how bad an actor is and demands a better one, and they bring in Charlton Heston to do the scene.And he does it beautifully.
That wasn’t Robin Williams. It was Ray D. Tutto.
For those who haven’t seen Baron Munchausen, Robin Williams has a completely lunatic - le mot juste - role as the King of the Moon in which he introduces himself in Italian: Re della Luna, or, “as everyone can call me now, Re di Tutto - the King of Everything.” Maybe he liked the title.
Robin Williams also has an uncredited cameo in Bill & Ted’s Excellent Adventure. Very brief, not in IMDb, points for spotting it. 
My Google-Fu doesn’t give me anything on this. Can you elaborate?
I suspect it is a heavy-handed reference to “The Rumble in the Jungle”
When was this movie made? I think that Carl Switzer (Alfalfa) was killed in the 1950’s.
One of the prizes at a charity auction was an extra spot on How I Met Your Mother. The winner turned out to be Conan O’Brian. The writers wanted to give him a speaking bit, but he insisted on only taking the extra spot he’d won.
So in once episode, while the characters are talking at the bar, you can see the rather large frame of Conan having a drink in the background.
Gosh, if it’s not on Google it must not exist.
When Bill and Ted land in the old west, there’s a cowboy climbing into an adjacent outhouse. You only get one quick look at his face, but once you see that flash of blue eyes the rest of the performance falls into place. He’s credited as “Dusty O’Dee,” who has only one other B-movie credit in the same time frame. I haven’t seen the latter movie and it could be another actor altogether.
I suspect there are quite a few crypto-cameos by Robin Williams in this era, waiting to be noticed.
In that same vein, there’s a cameo of John Ratzenberger in an early episode of Moonlighting. In the freaky first-season ender that featured Whoopi Goldberg, they end up running off the edge of the set and through the studio lot. The bad guy, played by Judd Hirsch, ends up getting a ride with a grimy old-west cowboy on a horse. It’s unquestionably JR, but the credit is another one-shot goofball name.
I have pictures (screencaps and comparison photos) somewhere.
Lou and Andy from Little Britain have a bizarre cameo in the Australian soap opera “Neighbours”
When was this movie made? I think that Carl Switzer (Alfalfa) was killed in the 1950’s.
Must be one of those strange urban legends, according to IMDB neither actor appeared in The Little Rascals.
Nobody from the original Our Gang/The Little Rascals movie series was asked to do a cameo or to consult or do anything else for the 1994 movie The Little Rascals.
The surviving people from the original series were not happy about being ignored like that.
Resurrecting a nearly 10 year old thread, sorry/not sorry 
Watching ‘Philadelphia’ (old movie from 1993 I believe), starring Tom Hanks and Denzel Washington. Synopsis is Tom is a gay bloke who is HIV positive with not too long to live. Denzel is a homophobic lawyer who represents Tom in a wrongful dismissal case.
Well into the movie, Tom throws a party to celebrate his near end of life. And who should pop up in the scene, but a non-credited QUENTIN CRISP, looking as queer and curmudgeonly as his writings described.
I got two:
At the end of Robin Hood: Prince of Thieves, King Richard makes an appearance, played by Sean Connery — a touch of class, but too little too late.
2010, The Year We Make Contact, has the voice of SAL9000 played by Candice Bergen, using a fake name.
There’s an episode of the Office where Michael is in New York, standing in Rockefeller Center just outside 30 Rock, and he thinks he sees Tina Fey walking by. He runs after her saying “Excuse me…” and when she turns around it’s a woman on the phone who looks like Tina Fey but isn’t. Meanwhile Conan O’Brien walks right past him going the other way towards 30 Rock and he doesn’t even notice.
Guns N’ Roses were briefly in two scenes in The Dead Pool. The murder victim, played by Jim Carrey in one of his earliest roles, is a rock star who’s “hit” song is “Welcome to the Jungle.” The band appears at his funeral and in an earlier scene shooting a harpoon for some reason.