Thumbelina does ask the bird to take her home several times. The bird genuinely thinks that it's more important to abandon her in favor of finding Cornelius. Yeah.
Scooby-Doo and the Cyber Chase is guilty of this. Someone created the virus. No one knows who. They get zapped into their friend's game, which is based on them. Can't they just get pulled back out? Of course not! Turns out the "geniuses" that made the special laser and game didn't think to make an emergency escape program. That's not all. The virus, for some reason, likes to make baseball references, constantly. Does the gang figure out who made the virus straight away? No. They make it to the final level and face off with the virus. The reveal of this "mystery" is that Bill the baseball fan was the one who created the virus. Nice job, gang. That was a tough one.
Right after Springfield is sealed in the dome, Professor Frink reveals that he has a laser drill that can break through it, but it's outside the dome. The trapped Springfield residents could have dug a tunnel under the dome, retrieved the drill, and started breaking through. Not a single person in town figured this out, even AFTER the Simpsons escaped the dome via the sinkhole in their back yard.
The residents spend most of the episode oblivious to the possibility that their problems could be solved with an old-fashioned town hole digging (Willie asks himself why he didn't think of that), and it is a guest star (Sting) who is the best digger. Springfieldians just are not very smart, especially when it comes to digging holes, since moreover in another episode they dig themselves into a hole and their plan for digging their way out is to "Dig up, stupid." The real idiot plot in this movie is Homer dumping waste into the lake after he was warned by his non-idiot daughter that this would be the death of everyone and everything he loved. But then again, it's quite common for Simpsons plots to exist because Homer willingly crippled his IQ (with a crayon) and did something stupid. Lampshaded in a later episode wherein the townspeople discuss the possibility of containing Springfield with a dome. Digging is mentioned.
The last third of GumbyThe Movie falls into this. Someone even suggests calling the police after the blockheads have Gumby and the band kidnapped, but the agent says "No time for that". While it thankfully turns out well with the blockheads tied up and the robot substitutes deactivated...They literally just leave the blockheads tied up...in their lab...and within a meter of the controls.
Were Back A Dinosaurs Story: A scientist from the future goes back in time and collects dinosaurs, force evolves their brains so they're just smart enough to be able to speak and reason on a fourth grade level (except poor Dweeb, who's basically left functionally retarded), brings them to modern day New York and then just drops them off in the city with very vague instructions of finding a fellow scientist without any training or understanding of how modern life functions. The entire city mistakes them for balloons, until one girl points out they're not, just because they happen to be marching with the Thanksgiving Day parade, never mind the fact that they are dancing and singing. Then a good chunk of the plot revolves around the dinos stumbling into trouble, being chased by the authorities and then trying to rescue two kids who stupidly signed a contract with an obviously creepy old circus owner. The time traveler comes back to save everything, but after all the madness has happened, not before. If anybody in the movie put more than three seconds of thought into their actions, it would be a pretty short story.
My Little Pony Equestria Girls. Despite Twilight giving an explanation as to why she can't simply explain to Celestia (or use her talking dog), it is never explained why Twilight or Sunset couldn't simply try to steal the crown back, or why Sunset couldn't think out her plan.
The LEGO Movie has an in-universe example; The popular Show Within a ShowWhere Are My Pants? has exactly one joke: a man can't find his pants. For every episode.When Wyldstyle hijacks the show's set to make a broadcast, she throws a pair of pants at the actor, declaring "Found your pants! The series is over!"