Imagine this from the perspective of a child. If you grew up with a pet odds are you also experienced the death of said pet. This is a huge deal for kids, as it is often their first experience with death.
Here's what happens in this episode: The family wakes up in the morning and can't find their beloved pet. Since both the kids and parents have to be at school/work they must go about their day and hope their pet will turn up later. When the family returns home they find their pet's corpse, stone cold dead in the garage.
I cannot figure out what Enter was going for with this plot thread. Is this supposed to be a joke? Are we supposed to be sad and, if so, why is Gumdrop's death brushed off so callously? The scene where the family finds Gumdrop is presented like a death scene except that it's brushed aside too quickly without any consequence. Why didn't he just do what anyone with an ounce of understanding would do and turn Gumdrop from a pony into a dog or cat? Or even a goldfish? Anything would have been better than killing her.
I know the answer to all these questions is autism, but god damn.
She changed from a pony into a motorcycle, which is basically the same as killing her, especially with how the scene is written.