What major event occurred in "The Rugrats Movie"?

The major event in The Rugrats Movie is that Baby Dil was born. Dil Pickles is introduced as Tommy Pickles’s baby brother in the 1998 animated film.

At the beginning of the movie, Didi Pickles gives birth unexpectedly early to a boy named Dylan Prescott “Dil” Pickles. Tommy initially worries that the new baby will change his family and take attention away from him. Dil’s arrival becomes the central family event that drives the story.

After bringing Dil home, Stu and Didi struggle with his constant crying and demands. Tommy and the other babies also find Dil difficult to understand, so they decide to take him back to the hospital using Stu’s motorized Reptar Wagon. The plan goes wrong, sending the babies into the wilderness and creating the movie’s main adventure.

Dil’s birth is not just background information: it establishes Tommy’s conflict and leads to his emotional growth as an older brother. Dil later appears throughout the Rugrats franchise and in the sequel series All Grown Up!.