The scene in which Tommy was about to pour the 'bananners' on Dil was a reference to the story of Cain and Abel, as pointed out by a Youtube commenter.
Lil seemed the most excited when Tommy's diaper was pulled down. Not only did the episode 'Naked Tommy' once air, but as a female, Lil is probably amazed by male anatomy.
Dil doesn't seem like he can talk; as shown in a few scenes, he can, but even then, it's only a few words. That, and as a newborn (at least a month or two old by the end of the film,) he probably doesn't have much to say, or is too busy acting bratty to care.
Despite most people disliking Dil's portrayal here, this is actually probably a more realistic portrayal of a newborn/month old than a show like Rugrats would lead us to believe.
According to the Mother's Day special, Tommy was born a premature kid; this means Didi already has an high risk of having premature births in later pregnancies, and we see that, in the movie, Dil is also born a week before expected. She probably learns from this as she never has any more children rather than risk serious complications again.
In the party scene, Angelica pretty much tries to scare Tommy by saying he shouldn't be so excited about the arrival of a new baby. Mainly because the baby will be getting all the love and attention, while his parents will forget all about him. While it could just be Angelica being her usual self, remember that when Charlotte thought she was pregnant, Angelica had a nightmare about this very thing. Except, while Charlotte's pregnancy ended up being false, Didi's isn't so in her own way she's just giving Tommy a heads up. Granted while Didi and Stu do pay a little extra attention to Dil at first, this is because he's a newborn and Dil isn't evil like the baby in Angelica's dream.
The monkeys being able to pull off that energized musical number (complete with choreography) makes a lot more sense when you remember that they're circus performers.
Many people see Dil as a brat and a terror. However, based on the evidence it is clear that Stu and Didi actually gave Dil colic. A common disease for babies, this causes pain, especially at night, crying fits, and digestion issues. All things Dil has. Considering we see Dil drinking the same milk as Tommy (and the Pickles' money problems) Stu and Didi never bought Dil baby formula and just gave him whole milk like Tommy, causing the problem.
We know Tommy was a preemie. It is very likely the hospital would have told them to give him a special formula, so that by the time he was off it he just went straight to whole milk. They just assumed they could start Dil on whole milk too.
Dil probably doesn't really have digestive issues — he's a newborn, and newborns' poop is often runny because they're not having solid food (so all that's in the poop is liquid and dead cells).
Ranger Frank is last seen too busy sobbing hysterically about the "dragon" he saw to be of any use to the parents. Later, when Stu finds the babies, he crash-lands his Dactar glider into the ranger cabin, which instantly collapses. Did Stu unwittingly kill Ranger Frank?! Or did Frank escape and go home after Margaret left with adults?
Actually, it was a shed in front of the ranger cabin. It's just that the scene happens so quickly, it's hard to tell without freeze framing it.
Given that it was Angelica's bad (and loud) singing that caused Didi to go into premature labor, who's to say that a similar incident didn't happen with Tommy? Or, considering Tommy was also a preemie, was it not caused by the singing at all but rather a condition Didi has?
With the reveal that Rugrats happens to share the same universe as The Wild Thornberrys where all animals are sentient, that means Scar Snout the wolf is fully aware that he’s hunting and trying to kill human babies and he comes off as gleefully sadistic.
