When purple rhinoceros Smoochy, a.k.a. kids’ television show host Sheldon Mopes (an interminably cheerful Ed Norton) has his first encounter with the seedy underbelly of network television, he laments to his agent, “What kind of world are we living in?” His agent Burke (actor-director Danny DeVito) bitingly responds, “The real one.”

But this is not the world that DeVito’s latest film depicts. “Death to Smoochy” is mostly a head trip of zany, overdone characters living in a bizarre fairy-tale world. If anything, it is the real world filtered through the lens of a Smoochy fan after one too many Smoochy Colas. The children’s television show host angle backfires for DeVito and writer Adam Resnick, who forgo dark comedy for under-the-top screwball antics.

After his predecessor Rainbow Randolph Smiley (the uninspired Robin Williams) is nabbed with an embezzlement charge, Sheldon is discovered at his main gig — the Coney Island Methadone Clinic. Despite the shady scenario, the introductory scenes are colorful and exuberant, setting the tone for the remainder of the film, even when it attempts dark humor.

As Sheldon bites into a soy hot dog, he delivers a veritable kiddie show manifesto to Nora Wells (Catherine Keener), the vice president of development at scandalized network Kidnet. The VP has no choice but to buy the “this-rhino-came-from-my-womb” schtick and hire Sheldon — the only talent without a dark past.

Norton delivers na•vet* and overall nuttiness that befit a guy who likes to dress up in a purple rhino suit and sing songs like “My Stepdad’s Not Mean, He’s Just Adjusting.” He maintains a curious balance between acting like a clueless dolt and being overly aware of his character. His ability to avoid mocking Sheldon makes the character somehow loveable, even if his singing makes you want to kill yourself.

The rest of the movie might have been funnier, however, if it indulged in some mockery of its own. Instead of being darkly funny, Sheldon’s enemies are as blindly bent on vengeance as he is on endorsing organic cookies sweetened with juice. Randolph is a rather unfunny borderline psycho who, at his lowest point, douses himself with gasoline in the middle of Times Square. Williams indulges himself in a series of imitations and exaggerations that don’t amount to the comedic comeback role he might have imagined.

Although Williams performs a few truly unbearable scenes — including a musical tap sequence on the sidewalks of New York — Resnick does deliver a few choice lines for the comedic veteran who recently suffered a bout of poor career choices. He elicits a few laughs when he lures Smoochy into a trap by promising him a meeting with “an orphan with mild asthma.” The film is best when it allows for sarcasm and a shot of cynical reality in the arm of Smoochy’s colorful kiddie world.

Keener’s role appears to be made to offer such cynicism, as she plays the tough-as-nails, no-frills female exec. But all the juicy bitchiness that Keener once displayed so well in “Being John Malkovich” is completely absent here.

Where Nora fails, the sleazy agent Burke succeeds — to a point. DeVito’s character offers much of the darkness to “Death to Smoochy” as he freely deals with mobsters and thugs who represent various interest groups and charities. But all too often, even DeVito’s cynicism is undercut by cinematographer Anastas N. Michos’s wild camera movement, quick cuts, and extreme zooms. The visual production makes the film seem like a kiddie show itself, where it should preserve contrast between the saccharine world of Smoochy and its off-camera corruption.

Slowly, as Sheldon comes to the realization that the world is not safe for Smoochy, he starts to take matters into his own hands. He even fumes at Nora, “I am not your puppet!” Again, Norton anchors “Death to Smoochy” — when he becomes dark, the film follows.

While that trend is commendable, the conclusion of “Death to Smoochy” breaks into all-out mad-cap antics. However much the title suggests a dark comedy, “Smoochy” is in the end a colorful picture book of a film. The concluding Smoochy on Ice number — an allegorical trip through the rest of the movie — is pretty much all you need to see.

“Death to Smoochy” projects itself as a dark comedy, but it seems more like DeVito’s hallucination put to paper. Its forays into black humor are somewhat successful, particularly when Sheldon engages in some corruption of his own.

Similarly, its all-out antics amuse at points — but neither type of humor is consistently effective or fully developed. One undercuts the other and forces DeVito to rely on mocking the mentally retarded and making Williams slam into walls. “Death to Smoochy” should have been as bitingly dark as DeVito’s “War of the Roses,” or perhaps as crazy as his “Throw Momma from the Train” — but it ends up an unhappy medium.