Rugrats - Season 2 - Eps 28: Visitors From Outer Space
Angelica and the babies are kidnapped by an alien ship and find out about their parents - they're all aliens, including Grandpa! Tommy and the babies search for a way to get out and meet a dude that knows the ways out. He takes Angelica and puts her in the middle of a deserted place.
About Rugrats

Title: Rugrats
First Air Date: 1991-08-11
Last Air Date: 2004-08-01
Status: Ended
Rating: 7.598/10 (from 703 votes)
Language: EN
Seasons: 10
Total Episodes: 322
Network: Nickelodeon
Genres: Family, Animation, Kids, Comedy
Production Companies: Klasky-Csupo, Nickelodeon Productions, Nickelodeon Animation Studio
Synopsis
Focuses on a group of toddlers, most prominently Tommy, Chuckie, Phil, Lil, and Angelica, and their day-to-day lives, usually involving common life experiences that become adventures in the babies' imaginations. Adults in the series are almost always unaware of what the children are up to; however, this only provides more room for the babies to explore and discover their surroundings.
Cast

E. G. Daily
Tommy Pickles (voice)

Kath Soucie
Phil DeVille / Lil DeVille (voice)

Cheryl Chase
Angelica Pickles (voice)

Dionne Quan
Kimi Finster (voice)

Tara Strong
Dil Pickles (voice)

Joe Alaskey
Grandpa Lou Pickles (voice)

Melanie Chartoff
Didi Pickles (voice)

Tress MacNeille
Charlotte Pickles (voice)

Jack Riley
Stu Pickles (voice)

Cree Summer
Susie Carmichael (voice)