[Editor’s Note: The following review contains spoilers for “Rick and Morty” Season 4, Episode 6, “Never Ricking Morty.”]

For a few fleeting moments on a Sunday night in May 2020, the world held the promise of a Birdperson musical. After a four-month hiatus in between halves of its Season 4, “Rick and Morty” returns with “Never Ricking Morty,” an episode chock-full of those kinds of tiny offshoots from a river of winking nods with even more volume than is normal for this show. (Between the headline and that last sentence, we’re already through two forced, not-quite-applicable metaphors. Apologies, but this is an episode that invites them more than most.)

Peel away the nested array of self-aware story references and this episode’s plot is fairly simple: Rick and Morty are trapped on a literal story train, winding through various cabins as the vehicle surrounding them barrels through the fourth wall and a few more after for good measure.

Starting in what looks at first like an episode that might jettison Rick and Morty entirely and focus on the various humans and creatures they’ve wronged in their travels, the train they’re on slowly gets revealed as a giant struggle to escape their own storytelling conventions. Each new car is another element of past stories — Rick’s many intergalactic flings, unexpectedly skilled hand-to-hand fighters, and more than a few markers that suggest none of this is actually happening.

It’s a dangerous exercise, given how a lot of these ideas are ones that the show has engaged with before, but never in such a threaded way. Rather than take the clipshow approach of “Morty’s Mind-Blowers” and the twice-name-checked-here “Interdimensional Cable” chapters, “Never Ricking Morty” puts all of these gags to a greater purpose, nodding to anyone who might see the show’s approach as gradually formulaic and using that approach to its own new ends.

Traveling through the different-styled cars, each with their own purpose, makes this feel like “Rick and Morty” taking on these conventions by way of “Snowpiercer,” complete with a de facto train conductor Storylord (the ever-welcome Paul Giamatti) serving as the Ed Harris of this whole enterprise. (With the HBO Max launch on the horizon, how’s that for unintentional corporate brand synergy?)

Not that any “Rick and Morty” story is a leisurely stroll through an alternate dimension, but this might be the densest episode since “The Ricklantis Mixup.” It’s helped along by the unfamiliar setting (the only trips to the Smith house are the Bechdel Test cutaway and the last scene in the living room — with the jarring side-angle view of the couch, that second one almost doesn’t count) and a lack of a cold open that wastes no time getting right into the thorny thicket of the train.

Even with this onslaught of callbacks and Ruth Bader Ginsburg cameos and literal Snowball fights, “Never Ricking Morty” doesn’t feel overstuffed. The brisk pace is more in line with the last episode’s Snake History bit, flinging a lot of information in a measured, concentrated dose. This story does have the train structure as a helpful home base, even when things swing between inside and outside its walls. For a show that once had one of its title characters call out “Inception” for being dumb and nonsensical, there’s a blend of nested levels here, whipped through with such abandon that it’s hard not to at least smile at the scope of the thing as it’s happening.

At the risk of too much armchair psychology, the two best episodes of “Rick and Morty” Season 4 have been built on the show working through its anxieties. Kicking off with an episode about the dangers of wish fulfillment, there were chances to address the entitlement of certain rabid sections of the show’s fandom. Here, “Never Ricking Morty” sure seems like a show barely halfway into a giant 70-episode order trying to assure both itself and its audience that it has enough in the tank to get to a far-off finish line.

“Rick and Morty” has always carried a cloak of insularity that it could always argue was more for Rick Sanchez the character than the show overall. Even the Season 4 toilet planet episode (which, admittedly, works better on repeated viewings than it does on first glance) has some element of acknowledging that Rick’s fenced-off nature has its shortcomings. When the closest thing the mad scientist has to a friend is his grandson, there’s a shelf-life to these twisty, one-off adventures. “Never Ricking Morty,” in execution, shows that there’s still enough in the tank for something to still feel fresh, but the threat of that “Broad Appeal” temperature gauge is probably there for a bigger reason.

Even the episode’s (possibly literal, depending on your particular viewpoint) deus ex machina has the getting-out-in-front-of-it questioning how a certain section of its audience might see that climactic Storylord exit. Still, the train-derailing moment shortly after is in line with the whole episode’s approach to having its cake and commenting on the fact that it’s eating it, too. (Hooray for more mixed metaphors!)

And both of the Season 4 half premieres have managed to work in the show’s own self-referential nature for its own benefit. Want to go back to Blips and Chitz and make sure it’s not just “Roy” Part II? Then have a guy get dismembered and float above a fleet of horrified arcade-goers. Worried about overdoing the Meeseeks thing? Do what the season premiere did and present them as some tacit warning about wanting too much of what may only have been good when it was unexpected.

From a creative standpoint, it’s hard not to measure an episode like this against how much runway it leaves the show overall. Is it closing off avenues for future stories by exhausting so much of its one-off potential all at once? Or is this somehow a weird act of self-preservation by working through some of its criticisms in the open? For now, “Never Ricking Morty” feels like the second option. As long as there’s something about this show’s approach that still manages to feel new and exciting, try all the permutations you want.

Guest Star Recon: It’s a big night for Paul Giamatti, with “Billions” returning on Showtime and him voicing the would-be conductor of this symbolic runaway enterprise. Giamatti is the perfect kind of guest star for this show: someone with enough technical expertise to sink their teeth into playing an actual character, but to do it in a controlled way that’s not just unreserved vocal chaos. It’s the kind of warped gravitas you only get from a performance where the main goal is something other than “funny voice.” There are few actors more watchable (or listenable, in this case) when they’re reveling in their job.

And naturally, when faced with the choice to voice a globally-recognized redemptive figure, Christopher Meloni is a no-brainer. One can only imagine that the head-thrown-back pose was somehow modeled on him, too.

Grade: A-

“Rick and Morty” Season 4 airs Sunday nights at 11:30 p.m. on Adult Swim.

Sign Up: Stay on top of the latest breaking film and TV news! Sign up for our Email Newsletters here.