Stopped Reading Too Soon

A character -- either out of impatience or because of a distraction -- stops reading a text before it ends, and always before something critical to the matter at hand. Inevitably, Hilarity Ensues, as they frequently latch onto something early in the text that is either modified or contradicted entirely by the portion of the text they skipped.

Often happens when a Lethal Chef fails to read the whole recipe before trying to follow it - and (of course) does terribly wrong something that becomes obvious upon reading the next line. Characters who suffer from Attention Deficit Ooh Shiny are frequently subject to this trope.

Sometimes justified when the text is an impenetrable mass of verbiage, laden with Sesquipedalian Loquaciousness, or both.

Subtrope of Poor Communication Kills. Contrast Conveniently Interrupted Document and Lost in Transmission.

Examples of Stopped Reading Too Soon include:

Anime and Manga

In Love Hina Christmas Special: Silent Eve this is what sets off the whole Idiot Plot.
In Ranma ½, Genma Saotome trains the very young Ranma in the Nekoken technique (by dumping him in a pit full of hungry cats wrapped in fish) after reading a single page in a martial arts manual -- had he just turned the page, he would have seen that the next sentence basically said, "Only an idiot would do this, as even if it works it will drive the student insane."
In Bakuman｡ both the protagonists stop reading only a few pages into the book Iwase gave Takagi, one because he doesn't like the genre she wrote in, and the other because it was too "deep" for him. Thus they both miss the message she inserted between pages about halfway through the book.

Comic Books

The Joker in Joker's Millions (which was adapted into an episode of Batman: The Animated Series) stops reading the note he got with his Unexpected Inheritance and doesn't finish the rest revealing that most of the millions he inherited were counterfeit until he has spent the real part of it.

Film

Hellboy: a variation; Abe Sapien reads off the description for the Hellhound from a book to Hellboy. Hellboy supposedly kills the hellhound before Abe finishes, after which he mentions the last few sentences about resurrection.
Lampshaded in Dogma:

Loki: "Cardinal Glick cuts ribbon on Catholicism, Wow! campaign." And?
Bartleby: (sighing) You have to keep reading.

Literature

In The Incredible Journey a housekeeper finds only one page of a two-page note. This leads to confusion about who is going to be taking care of three pets for two weeks. This sets the plot in motion - the pets escape and have adventures before anyone realizes they're gone.
Moon Night by Stanislaw Lem had this as a punchline turning the whole plot into Black Comedy gold.
Goosebumps, "How to Kill a Monster", the two main characters are trapped inside their grandparent's house with a monster inside. They find a letter from their grandparents telling them they left and warns them about the monster inside. After killing the monster and escaping from the house and into the swamp at night, they continue reading the letter explaining their grandparents lock them inside for their protection and to prevent them from leaving the house because there are more monsters in the swamp and they come out at night. After they finish reading, the kids have no idea what they are going to do next.

Live-Action TV

In the episode of M*A*S*H where a "friendly" bomb falls in the middle of the unit, the doctors set out to disarm the bomb by following the instructions given by one of their colleagues. He stops reading at the wrong place ...
There's the Buffy the Vampire Slayer episode "Fear Itself" where Giles reads the information on Gachnar but doesn't read the inscription with its 'actual size' caption. Buffy also fails to let him finish reading later on before she breaks the seal and summons Gachnar on accident.
The Colbert Report and The Daily Show lampooned journalists for only reading page 1 of the Supreme Court's decision on the Affordable Care act ("Obamacare") and thus thinking incorrectly that the latter is declared unconstitutional. Colbert parodied it by reading comically inadequate amounts from A Tale of Two Cities (just "it was the best of times") and War and Peace (just "war" from the title).
The Twilight Zone had an episode where the protagonist is wary about trusting the aliens that recently arrived, but once an alien book's title is translated as "How To Serve Man"^[1] he's convinced enough to get onto their spaceships and take a trip to their home planet. The rest of the book is translated seconds too late to stop him.

Western Animation

On American Dad a guy stopped reading Carrie, literally in the middle of a sentence. Thus, he dropped pigs from the ceiling onto Stan at the prom instead of pigs' blood.
In one Road Runner skit, the Coyote sets out some birdseed bait spiked with "Earthquake Pills". But the Road Runner eats the bait with no effect. Disgusted, the Coyote swallows the entire jar of Earthquake Pills only to notice too late the fine print on the label: "Does not work on roadrunners".
In the episode of The Simpsons "Blood Feud", Homer writes an angry letter to Mr. Burns, which starts out as a fake thank you note. Mr. Burns at first reads the thank you part, and is deeply touched, until he later discovers the following sentences.

Dear Mr. Burns... I'm so glad you enjoyed my son's blood and your card was just great. In case you can't tell, I'm being sarcastic. You stink! You are a senile, buck-toothed old mummy with bony girl-arms, and you smell like an elephant's butt.

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