Can there be anything left to say about “Back to the Future?”

It’s been 30 years since Michael J. Fox’s Marty McFly first went back in time and came back to the future, and more than 25 years since “Back to the Future Part II” took us to that goofily retro-futuristic version of this past Wednesday — October 21, 2015 — with its hoverboards, flying cars, and holographic movie marquees.

“Back to the Future Day” has come and gone, and after all these years of looking ahead, the series is now “all back and no future,” as the headline of a brilliant piece by critic Matt Zoller Seitz put it earlier this week.

Did director Robert Zemeckis or his co-writer Bob Gale really think in 1989 that flying cars were 30 years off? Did anyone? I doubt it. Even in 1989, this segment reminded me of a song released five years earlier by the Christian band Daniel Amos, “(It’s the Eighties, So Where’s Our) Rocket Packs.” The song ironically contrasted a 1950s vision of a Space-Age future with 1980s reality. Some of the song’s future iconography is echoed in the 2015 of “Part II;” the lyrics mention tire-less (flying) cars, weather-controlling technology, and picture phones in every home (the last of which, at least, has more or less come true, almost as imagined in the 1989 film, via Skype).

One might say, then, that the 2015 of “Back to the Future Part II” is as much a 1950s vision of the future as a 1980s one, and to that extent a vision that by the 1980s was already showing its age. It’s the futurism of Walt Disney’s Tomorrowland theme-park vision, of “The Jetsons.”

Marty’s arrival in the Hill Valley of 1955 in the original is full of winks at the quaintness of the past, from “Mr. Sandman” and “The Ballad of Davy Crockett” to the uniformed service station attendants smartly rushing over to polish up a car pulling in for a fill-up.

But Marty’s arrival in the futuristic Hill Valley of 2015 can equally be seen as a send-up of the 1950s — that is, of its naive, already-dated Space-Age futurism. (Lines like “Boy oh boy, Mom, you sure know how to hydrate a pizza” sound particularly “Jetsons”-like.)

It’s been widely observed that any period setting in any film, past or future, is ultimately at least as much about the time period in which the film is made as it is about the putative setting. It’s no surprise to see the 1980s referenced in 2015, most notably in the “Café 80s” sequence, with Michael Jackson’s “Beat It” playing in the background and digital simulations of Ronald Reagan and the Ayatollah on a TV screen taking Marty’s order.

In effect, the whole trilogy is a kind of “Café 80s,” including the segments set in the past.

But we also find elements of 1950s culture, for instance, in the Old West of “Back to the Future Part III.” “Far out!” Marty says when he notices the Frisbie brand name on a pie plate before tossing it like a Frisbee (a 1950s invention) to disarm “Mad Dog” Tannen. In a sense, the whole setting and genre of “Part III” evokes the 1950s, the peak decade for the Western on the big and small screens. (Western films in the 1950s outnumbered films of any other genre, and perhaps all other genres combined.)

All in all, the whole trilogy, regardless of temporal setting, can be seen as a kind of dialogue between the 1980s and the 1950s. It’s no accident that the soundtrack signature song for the 1980s, “The Power of Love,” was recorded by Huey Lewis and the News, a very 1980s band that nevertheless drew inspiration from the 1950s, from doo-wop harmonies to their very name.

Of course, it’s a dialogue between the 1980s and the 1950s on 1980s terms. It may have been easier for the filmmakers to get the period details right in 1955 than 2015, but even fond nostalgia somewhat distorts its subject, as the Café 80s distorted its own theme.

“One of those nostalgia places, but not done very well,” Doc Brown says in a line that can be taken both as a sly counterpoint to the film’s own sure-to-be-falsified picture of 2015 and also as a tacit admission that if 2015 could get the 1980s not quite right (even in a film made in the 1980s!), the series’ own portrayal of 1955 is also a product of its own time. (Another nod in this direction: Doc Brown’s unsuccessful attempt, based on Western movies, to attire Marty for his journey to the Old West.)

Among the film’s various themes and angles on its implications (social, cultural, political, economic, etc.), one of the more notable has to do with sexual mores in the first film.

The original timeline emphasizes the generation gap between the 1950s and the 1980s. In early scenes, Marty’s strait-laced, prudish mother Lorraine (Lea Thompson) disapproves of forward girls like Marty’s girlfriend Jennifer (Claudia Wells in the first film), and would certainly never approve of Marty’s secret big date with Jennifer, a night up at the lake.

“When I was your age I never chased a boy, or called a boy, or sat in a parked car with a boy,” she frets.

“I think the woman was born a nun,” Marty tells Jennifer later.

“She’s just trying to keep you respectable,” Jennifer teases.

The truth, of course, is quite different. Stranded in 1955, Marty is dismayed to discover his teenaged mother as a bashful but boy-crazy beauty who takes an alarming interest in him and is eager to park on their first date.

“I’m almost 18 years old; it’s not like I’ve never parked before,” she says with a smile, so we know this side of Lorraine isn’t just a result of Marty contaminating the timeline.

She’s wearing a daringly lowcut strapless dress — and then she takes a furtive swig from a flask that she laughingly explains she “swiped” from “the old lady’s liquor cabinet.”

“Yeah, well, you shouldn’t drink,” Marty tries to tell her.

“Why not?”

“Because, you might … regret it later in life.”

“Marty, don’t be such a square,” Lorraine frowns. “Everybody who’s anybody drinks.” Then she lights up a cigarette — and, to Marty’s predictably shocked response, says in dismay, “Marty, you’re beginning to sound just like my mother.”

The point, of course, is that the more things change, the more they stay the same; that parents and children are not so different as the latter might think and even as the former might pretend.

Moreover, the 1950s weren’t as different from the 1980s as it might seem. The sexual revolution of the 1960s changed many things, but it was a change in attitudes, not human nature.

In the end, the ripple effects of Marty’s brief but decisive involvement at the outset of his parents’ romance transform Marty’s family life for the better in 1985. His parents are happier, better adjusted, and generally better off, and, pointedly, Lorraine’s sense of propriety is much more relaxed; she now likes Jennifer, and even knows about and approves Marty and Jennifer’s “big night” at the lake.

Clearly, the 1980s has something that the 1950s needed, and everyone is the better for the encounter. Even bullying Biff (Tom Wilson — a practicing Catholic and musician who has recorded religious music) has, in a sense, been transformed for the better, having been deflected by a knockout punch from Marty’s father George (Crispin Glover) from a life of domineering workplace bullying to cheerful obsequiousness as an auto detailer.

At the same time, there’s a bit of comeuppance for Marty’s cocky attitude about his mother’s original narrow-minded views. While there are obvious Oedipal reasons for Marty’s profound discomfort with young Lorraine’s ready sexuality, his dismay at her drinking and smoking suggests that his unease with her permissive attitudes goes deeper than this.

If the early scenes with Marty’s mother suggest that parents sometimes try to hold their children to a standard they never tried to meet themselves, the parking scene suggests that the reverse may also be the case: Children may want their parents to embody a higher standard than they want for themselves.

Marty may not want his mother to keep him “respectable,” but he doesn’t want unrespectable behavior from his mother.

Platitudes like “You might regret it later in life” may ring hollow coming from our parents when we are young, but what goes around comes around, and the tendency to become one’s parents can catch up with us when we least expect it.

I remember watching “Back to the Future” with my parents, and now I’ve watched it with my own kids. As a teenager I identified with Marty, and I still do today, as much because of when it came out and when I first saw it as because that’s just the movie’s point of view.

But I view teenaged George and Lorraine differently. They make me think of my parents as teenagers, something far easier for me to imagine today than it was when I was a teenager and they were younger than I am now. I think of things that happened in their lives and in mine that might have happened differently, things regretted later in life, that no time machine will ever undo.

And I look at my own children, and I see all too clearly the adults they will become sooner than they can imagine, and I think about them looking back — perhaps watching “Back to the Future” with their own kids — on the immutable past, which is unfolding right now.