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.
Anvilicious: There is nothing in the world more anvilicious than this special, except possibly flashing "DRUGS ARE BAD FOR YOU" for half an hour (which might be just as entertaining in a weird way, if not more so).
Family-Unfriendly Aesop: Michelangelo of the Teenage Mutant Ninja Turtles chastises Mikey for trying to get his wallet after it's stolen. Bear in mind that not 5 minutes ago, Mikey was chastised for stealing a piggy bank. Stealing is bad, getting your stolen things back is also bad? It could be Hand Waved as Michelangelo getting Mikey to focus on one thing at a time, because as we all know, drugs are more important than money.
Bugs Bunny knowing what a joint is isn't that crazy. HE'S AN ACTOR. On top of that, the Looney Tunes cartoon series isn't really meant for children (though there wasn't much drug references, besides the usual alcohol, tobacco, and perscription meds), so yeah, Bugs would know what marijuana is.
ALF was once addicted to cotton in the live-action version of his show, which makes him act both high and drunk, so it would make sense for him to appear in this special. Also, the sitcom ALF was written and created by a Hollywood writer who was on drugs.
An in-character explanation is that Michelangelo would know the most about drug related temptation.
Simon is the Smart Guy of the Chipmunks. He's supposed to have knowledge of surprising things.
The reason why the toons were being such dicks to Mikey might be a parallel to drugs. At first, they seem to be helpful and good, but later down the line, they screw you over big time. It makes more sense if you accept the theory that the toons are hallucinations from the drugs.
Fridge Horror: The above brilliance is a double edged sword. At some extent, our classic childhood heroes know about drugs. Doubly so for Alvin and the Chipmunks if you know even the slightest thing about celebrity scandals.
Nightmare Fuel: Never mind the overall bizarre tone of the special. There's a truly mind-breaking dream sequence right about when Mikey hits rock-bottom.
They Wasted a Perfectly Good Plot: An official crossover starring popular characters from all of Western animation. Too bad this coincided with a preachy special about a teenager with drug problems.
What Do You Mean, It Wasn't Made on Drugs?: Considering the intent of the special, that's a stupid question to ask. Then again, if you look at it with a cynical eye, then it does feel like someone had to have been on drugs to come up with something this batshit insane. Simon from Alvin and the Chipmunks explaining what marijuana on its own is a little mind-bending.