>> when the script breaks the 4th wall?

[LilCerberus]

Still probably not what Zombie's looking for, but:
Blazing Saddles (1974)
The French Mistake scene, even as a little kid was something of a foregone conclusion, but where the sequence ends with Hedley Lamarr (Harvey Korman) hiding out in Grauman's/Mann's Chinese Theatre, and he looks up at the screen.....

I'm watching Beyond the Law (1968) while listening to a radio documentary about Hedy Lamarr that's got that nagging me...

[LilCerberus]

What about that episode of 3rd Rock From The Sun, wherein William Shatner & John Lithgow make mutual reference to Nightmare at 20,000 Feet?

[RCMerchant]

In the HOUSE THAT DRIPPED BLOOD (1971 ), John Pertwee plays an aging horror film actor and says-

" That's what's wrong with the present day horror films. There's no realism. Not like the old ones, the great ones. Frankenstein, Phantom of the Opera, Dracula - the one with Bela Lugosi of course, not this new fellow."
He's referring to Christopher Lee, of course- who just so happens to appear in the film as well!

[ER]

Howard Hawks' His Girl Friday, from back in 1940.

[Gabriel Knight]

BEING JOHN MALKOVICH breaks it in the sense that he's an actor playing himself in real life. The rest may be fictitious, but as far as we know, he's not.

[RCMerchant]

In BELA LUGOSI MEETS A BROOKLYN GORILLA (1952) the Jerry Lewis wannabe says to Lugosi- "Your that guy from the movies who scares little kids!"

[Morpheus, the unwoke.]

Woody Allen breaks the wall several times during 'love abd death'.

[Trevor]

George Lazenby in OHMSS: "This never happened to the other fella" 

[LilCerberus]

Porky's 2: The Next Day
     The leg from A Christmas Story is the same one used in the sword fight scene during the school play, and I think the zombie was supposed to be a reference to Children Shouldn't Play With Dead Things.....

[Cult_Moody_Movies]

 Trading Places (1983) -

Randolph Duke: We are 'commodities brokers,' William. Now, what are commodities? Commodities are agricultural products... like coffee that you had for breakfast... wheat, which is used to make bread... pork bellies, which is used to make bacon, which you might find in a 'bacon, lettuce and tomato' sandwich.