Hollywood Mirage

The characters are stumbling through a desert, for whatever reason. They're unprepared, dehydrated and starving, desperate, depressed, generally in a sorry way.

But hark! One of the characters sees an oasis. Bright, glittering blue water, cool palm trees, in some cases girls in Arab garb. They sprint to it and fill their mouths with handfuls of refreshing water... and then the scene fades, leaving the characters to spit out their mouthfuls of gritty sand.

A Real Life mirage is simply an optical illusion wherein it appears that there is refracted sky (which looks like water) a distance ahead of you: this can happen in several climates, but seeing water in desert has a greater appeal. However, the term is also used for when someone has a hallucination, leading to this confusion.

Examples of Hollywood Mirage include:

Anime and Manga

In one episode of Speed Racer, this happens to Spritle and Chim Chim. It was quite a long sequence too.
In One Piece, the mirages Nami creates are...interesting to say the least. They properly use the idea of mirages being created by the differences in air density caused by sharp temperature differential, but they have Nami create mirages by standing behind the anomaly, which logically would reflect her image back at herself, not distort it for the enemy to see. It was used correctly the first time, though.
- Not even going into how she can supposedly control what is seen...
  - A lot of what Nami does in a fight, post Alabasta arc, pretty much can boil down to using her Clima-tact.

Comic Books

Happens to Tintin in "Cigars of the Pharaoh" and "Black Gold", and to the Thompson twins in "The Crab with the Golden Claws".
The Carl Barks comic "Mcduck of Arabia" had Uncle Scrooge and Donald Duck wandering in the Saudi desert. They see a mirage of a water cooler offering water at 10 cents a cup. Scrooge refuses to buy it--"we can get all the water we want for free back at our hotel!"

Film

A live-action version occurs in Abbott and Costello in the Foreign Legion.
A variant occurs in An American Tail II: Fievel Goes West, where Fievel saw his family while stumbling in the desert, but they turned out to be (apparently very small) cactuses. Tiger is going through the same desert and confuses an owl with his old girlfriend. The two then pass and ignore each other, because each thinks the other is another mirage.
Subverted in Looney Tunes: Back in Action—Bugs, Daffy, and their human companions see a mirage in the desert. Which turns out to be a conveniently placed Wal-Mart. "Convenient, or product placement?" Bugs wonders aloud.
Road to Morocco has a mirage of a drive-in, followed by singing mirage of Dorothy Lamour, who disappears when touched.
In the The Three Stooges short "We Want Our Mummy", Curly is convinced he sees the ocean in the middle of the desert and even goes "swimming" in it (in reality just flopping around like a beached fish); when he convinces Moe and Larry that the water is real, they dive into it and open a trap door into an underground tunnel.
happens multiple times during the trek across the desert in Carry On Follow That Camel.
Inversion in the 1999 Mummy film, Hamunaptra is hidden by a mirage (which makes it look like an empty desert all the way to horizon) until the rising sun reveals it.

Literature

In Robert E. Howard's "The Slithering Shadow", Conan the Barbarian is at first worried that what he sees, while dying in the desert, is just a mirage.

Video Games

Happens in Mario Party 3, somehow. In the desert board map, there's a 'mirage' form of the Millennium Star, which only vanishes when someone tries to buy a star from it (and beforehand, makes it appear like there's two of the character on the map). It'd probably be better called an 'hallucination'.

Western Animation

A Looney Tunes short shows Daffy Duck in the Sahara desert seeing things including an oasis and an old car.
When Donald Duck and Goofy get lost in the desert in Crazy with the Heat, Donald sees icebergs everywhere, while Goofy sees a soda fountain, complete with an Arab sheikh behind the counter. Unaware that it's a mirage, Goofy orders drink after drink, only to have them disappear in his hand. And yet the sheikh becomes very real when he demands payment... or else.
Stewie and Brian think they see a Dr. Pepper machine in the desert, but...nope, it's RC Cola.
In an episode of Inspector Gadget the titular character travels into a dessert and sees a lemonade stand. After realizing that it isn't real he then proceeds to assume EVERYTHING HE SEES from that point forward is "just a mirage." This includes the M.A.D. agents out to kill him, the sacred golden scimitar he is supposed to be protecting, a tree he bodily crashes into, Chief Quimby, a pit full of cobras...
In an episode of Garfield and Friends, Jon's car breaks down on a desert road, leaving him, Garfield and Odie stranded. As Jon goes to get the car fixed, Garfield explains and demonstrates the cartoon definition of mirages several times to Odie, including at least one Red Herring. The ending takes a turn for the Mind Screw when it's revealed that the guy who towed and repaired the car was himself a mirage.