These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Accidental Innuendo: In the PS1 video game Rugrats: Search for Reptar, this trope pops up during the Golf game stage:
Tommy: "We just gotta get the balls in the hole, and we'll get a whole mountain of ice cream!"
How the Toy Palace episode ended, with an animatronic Reptar pushing an animatronic gorilla into a time machine, sending it to the period when Washington crossed the Delaware River. And this wasn't one of the babies' Imagine Spots.
What about Taffy? She was a babysitter introduced late in the series who everybody on the show loved, but almost everybody watching it hated. She mainly existed so that Amanda Bynes could have another Nickelodeon show to star in.
Designated Villain: In one episode where both Drew and Charlotte tell Angelica they'll buy her a toy if she stays quiet for a half an hour. She genuinely tries to obey them but then the babies decide to exploit this to make a mess, enraging Angelica so much she finally snaps. She ends up getting blamed for the mess the babies made and doesn't get either toy.
"SING A HAPPY HAPPY HAPPY HAPPY HAPPY SONG, SING A HAPPY HAPPY HAPPY HAPPY HAPPY HAPPY SONG! SING A HAPPY HAPPY HAPPY HAPPY HAPPY SONG, SING A HAPPY HAPPY HAPPY HAPPY HAPPY HAPPY SONG! SING-" ... okay, you get the idea.
"Packed my white bread and salami (packed my white bread and salami)! Then said bye-bye to my mommy (then said bye-bye to my mommy)! She and Daddy cut me loose (she and Daddy cut me loose)! With a canteen full of apple juice (with a canteen full of apple juice)!"
Ensemble Darkhorse: Of the babies themselves, Chuckie and Angelica are by far the most popular—in fact, Angelica was the only one of the Rugrats to make it into TV Guide's 50 Greatest Cartoon Characters countdown. Her father Drew is one as well in recent years, thanks to Barney Bunch videos and his arguments with Stu.
Reptar has more fans on Facebook than the series itself does. This hasn't gone unnoticed by Nickelodeon, who released T-shirts of the character. Wearing one in public is bound to elicit smiles from passersby who fondly remember the show.
Fanon Discontinuity: When the series ended depends on who you ask. Before the first movie? After? Before the second? After? After the first series? And even the people who like All Grown Up! don't like to mention the third movie.
Friendly Fandoms: The Rugrats fandom and the Recess fandom are very friendly toward each other; a contributing factor would probably be because the latter was created by two Rugrats writers, Paul Germain and Joe Ansolabehere (And written by their writing team)
Genius Bonus: In "A Visit From Lipschitz" the song he's humming is the German national anthem. The "dog broomer's" name is Ilsa Umlaut. An umlaut is the little dots over vowels in Northern European languages.
Harsher in Hindsight: "The Santa Experience" has Chaz 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 Chaz. So much so that he's driven to stealing a Christmas tree.
In the All Grown Up! pilot, the main plot centers on Stu losing his lucky Scorpio medallion. Didi tells him "[He's] not a Scorpio. [He's] a Libra." Yeah, so is every Scorpio born before the year 2011 in the world now.
But only if you follow the Eastern Zodiac. The Western Zodiac is still twelve signs.
The episode of The Simpsons that aired in October of the same year (a month after) called A Streetcar Named Marge has a very similar subplot to The Big House. In the early days of Rugrats, they shared animators with The Simpsons as well as Nancy Cartwright (Bart) later voicing Chuckie.
There's an early episode of the Simpsons with a scene Bart flipping around a marker, with the focus of the camera tight on the camera. The style that the marker is drawn in is VERY similiar to the crayons in the opening of Momma Trauma.
In one episode, Stu gets a head injury that makes him think he's a baby, so he spends the entire episode wearing a diaper and answering to the name "Stuie". This was, of course, several years before another baby named Stewie became a pop culture icon.
In the 1993 episode "Game Show Didi", Didi is going up against a smart, undefeated champion in a game of Super Stumpers (a parody of the game show Jeopardy!) featuring Alan Quebec (voiced by Jeopardy! host Alex Trebek). Fast-forward to 2004, and Ken Jennings seems to fit the bill in a winning streak from June 2 to November 30 that ended with a total of $2,522,700. Not bad for a champ who was then undefeated 74 times!
"Visitors from Outer Space" included a quick background gag that involved heads in jars (two of which were Shatner and Nemoy).
In one episode, Chuckie comments that he was afraid of eating green Jell-O because it could've been alive. A couple of years later, Jell-O's slogan was actually "It's alive!"
In a similar vein, Dil and Kimi, both later additions to the show, had their voice actresses star on The Fairly OddParents. Tara Strong (Dil) went on to play Timmy, while Dionne Quan (Kimi) went on to play Trixie (who Timmy has a crush on!).
In the episode "Garage Sale", Didi gets mortified when the kids stumble upon her and Stu's old disco memorabilia, and when Angelica asks her what "disco" is, she tells her that "It's something that happened a long time ago, and it's never, never coming back!" (which is currently the page quote for Deader Than Disco). Years later, the Poorly Disguised Pilot for All Grown Up! would revolve around Stu and Didi competing in a disco dance competition.
Not to mention the fact he was literally "Disco Stu".
Incest Yay Shipping: Some people ship Chuckie and Kimi together. At least they are only step-brother and step-sister. Tommy and Angelica get shipped, but it's more rare.
Launcher of a Thousand Ships: Chuckie Finster has been paired with Angelica, Lil and Susie (and more) over the years. Though to be fair, in the original series Chuckie has had Ship Tease moments with all 3 of the aforementioned girls.
Tommy in All Grown Up! is also paired with just about every female character the show has.
In-universe example: the episode when the adults took down Chuckie's crib and replaced it with a bed. The first night Chuckie sleeps on the bed, a monster from under the bed keeps talking to him and telling him that he's going to eat him (not even Tommy heard the voice when he slept over the next night). When Chuckie first investigates, he's frightened, thinking he actually spotted a monster reaching at him, and Chuckie jumps right back into bed, frightened. But as it turns out, the monster was actually [Chuckie's dad] Chaz's sweater with one sleeve poking out, and the darkness concealed the cooler colors, making the sweater look threatening.
Rugrats: Scavenger Hunt for the N64 could count as well, for being a Mario Party rip-off with none of the exciting stuff that Mario Party had and instead, had a unnecessary life system based on cookies, the ability to get cards that were pretty much pointless, and overall, got boring really quickly. See here for a Let's Play on the game by two guys that grew up with the series.
Purity Sue: Susie's mother Lucy takes the cake with this one. A successful doctor, she benefits from Positive Discrimination and Women Are Wiser as episodes show her to be an incredibly gifted artist and chef who has studied in France. All Grown Up! takes this even further and reveals she was a successful blues singer at age 18.
Parody Sue: It's possibly intentional however, since her role in the first episode consists mainly of ex positioning her excessive history of talents to a rather dumbfounded Didi.
Rescued from the Scrappy Heap: There are those whom found Dil to be a lot more likable in All Grown Up! (in which even certain people whom did not like the show would agree to that). This is because while, in the original, he never really had a personality, in the sequel series, he became a weird, conspiracy-and-alien obsessed guy who just happens to like being an oddball.
Similarly, Kimi was also better recieved in All Grown Up! than she was in the original series.
Susie is also much less of an Ace/ Purity Sue than she was in the original series. In fact the first episode has her getting conned into giving a woman $1000 thinking it's for a record deal. Other episodes give her proper flaws such as worrying she's too perfect, becoming jealous of Angelica in her house and being unable to juggle two hobbies at once.
Within the show's staff, Angelica was hated prior to her Character Development in later seasons. Arlene Klasky in particular, who stated in excess how much she loathed the character initially, admitted her fondness for her by the time of the first movie.
Kimi to some of the fanbase. It doesn't help that she comes in right when the series had begun experiencing Seasonal Rot.
Dil also was not seen favorably by a lot of fans. Mostly because Dil was a baby that couldn't do anything, in a series where all the other infants walked around and could talk. Another character that failed to get much love from the fans was Taffy, the generously hyped up character introduced for multiple episodes and then vanishing.
Angelica has now become one with the rise of the 90sAreAllThat programming block in the vein of Brian Griffin from Family Guy. She had achieved a high rating in the Annoying/Hated fan voted category in the Top 10 Annoying Cartoon Characters countdown by Lew Toons, achieving third place just under Scrappy himself and Spongebob. This is significant because when the show was airing, Angelica was actually the most popular character on the show.
Angelica was in fact this to the actual creative team originally, Arlene Klasky in particular stated her hatred for Angelica throughout the early points of the show (though changed her tune as the show made gradual alterations to her).
Seasonal Rot: After the second movie and Kimi became a regular. Her presence did not ruin the show, however, it was the fact the Baby Talk was dumbed down. They dumbed down baby talk.
However, after Kimi's introduction they did begin basically recycling plots to shoehorn her in. For example, despite Rugrats having several holiday specials in previous years (including in the first season which dealt with the baby's first Halloween), after Kimi becomes part of the babies, the Halloween special is treated like the first with none of the babies nor Angelica remembering what had happened a 'year' ago.
Not to mention randomly retconning things: such as Tommy, Chuckie's, Phil, and Lil's first meeting, Angelika's first walk, etc. It was almost like the old writers had never seen the earlier series.
There are some fans who believe the show started to go bad after the 1997 revival, some after the first movie, some after the second movie, some after All Grown Up!, and the rest who either believe the show was sweet mana from above or jumped the shark from the beginning.
They Wasted a Perfectly Good Plot: In "Mommy's Little Assets" Drew and Charlotte debate about who's going to watch the kids. Drew's argument is that he's bungee jumping and "I can't take the kids up in the balloon with me, can I?" - oh if only...
Toy Ship: Tommy/Kimi, Chuckie/Lil, Chuckie/Angelica, Tommy/Lil among others.
The Woobie: Chuckie certainly has his moments especially during the Mothers Day episode.