In "The Santa Experience", Angelica meets a shopping mall Santa and one item she tells him she wants is a "911 working emergency stethoscope kit", pronouncing "911" as "Nine-Eleven".
A similar thing occurred in Rugrats in Paris (which released in November of 2000), in the opening scene when Chuckie is trying to count steps, he utters "Nine...uh, Eleven"
"The Santa Experience" has Chas lamenting that his childhood Christmases were never that enjoyable and he worries that it'll be the same for Chuckie. Fast forward to the Christmas Episode of All Grown Up! where we discover that Chuckie's Christmases are indeed miserable because of Chas.
A couple of episodes deal with Angelica's loneliness and jealousy of the babies' friendship, notably "The Unfair Pair" where she gets annoyed that the twins exclude her. By the last season she's the only one of the babies without a sibling — and "Sister Act" explores her wanting one.
In the 1994 episode "Pickles vs. Pickles", Drew's nightmare involves a pair of lawyers named "Alan Hershowitz" and "F. Lee Barnum"—thinly-veiled No Celebrities Were Harmed parodies of Alan Dershowitz and F. Lee Bailey—battling it out in a courtroom over his custody of Angelica. While you might think that's a reference to the O.J. Simpson murder trial, it's actually not: Nicole Brown Simpson was murdered just a few months after the episode aired.
Many things relating to Chas and Chuckie's relationship thanks to "Mother's Day":
"Chuckie vs. the Potty" has Chuckie describe getting potty-trained as "the worstest thing that's happened to me since my mom put me on the bottle." Perhaps she put him on the bottle because she knew she was dying. There's also the fact that he still remembers her in this episode, but by the time of "Mother's Day," his infantile amnesia seems to be kicking in and he only has dreams about her without remembering that she really existed.
Remember when Chas was crying his eyes out during Ben and Elaine's wedding in "Let Them Eat Cake"? There's a chance it's bringing up painful memories of losing his wife.
In "My Friend Barney," Chuckie having an imaginary friend is not too far off from how real-life children, and even adults, who are coping with loss often have imaginary friends so they can talk to someone as if they were physically present.
There's also "Dummi Bear Dinner Disaster," which makes a passing remark about Chas going to see a psychiatrist. If you think about it, it is implied that the death of Melinda left him an emotional wreck, and that the only thing preventing him from losing his sanity completely is their son Chuckie.
In the aforementioned "Chuckie's Wonderful Life," Chuckie sees that, without him, Chas' sanity is completely broken: he's unemployed and lives in poverty, with empty pizza boxes for furniture and a sock puppet as his only friend. Considering that he's lost his wife and Chuckie is their only son, this is justified... and heartbreaking.
"Vacation" has a scene in which Heimlich & Bob, parodies of magicians Siegfried & Roy, are attacked by their white tigers. Six years later, the real Roy Horn was attacked by a white tiger.
and F. Lee Bailey