The writers thought this scene was "too dark" and changed it to Homer getting a shotgun and going after the aliens, before finding out that Bart is playing a trick on him.
The writers thought. This was before finding out that Bart is playing a trick on him. This scene was "too dark". The writers changed it to Homer. The writers were getting a shotgun. The writers were going after the aliens. This was before. Bart is playing a trick on him. The writers were finding out this.