"It wasn't as good as the first one. But it was very successful."

That was the assessment by Steven Spielberg himself of "The Lost World: Jurassic Park," which marks its 20th anniversary on May 23, 2017. Indeed, the 1997 sequel may have prompted eye-rolling among fans, but it scared up a fortune at the box office, enough so that the franchise has continued to this day. Plus, it was the last time we got to see Jeff Goldblum's snarky scientist Ian Malcolm -- at least until next summer's "Jurassic World 2."

As smoothly as the production ran -- Spielberg finished it on budget and ahead of schedule -- there were still some surprises and jokes on the set. Read on for the dino-details.

1.Michael Crichton called his "Jurassic Park" follow-up novel the only book he ever wrote that he knew would be made into a movie. He took inspiration from Arthur Conan Doyle, who'd written his own dinosaur novel in 1912 called "The Lost World," and who had famously resurrected Sherlock Holmes after killing him off -- a precedent Crichton used to justify bringing back Ian Malcolm, who had survived in the movie version of "Jurassic Park" but not in Crichton's earlier novel.

2. Even so, Spielberg and "Jurassic Park" screenwriter David Koepp ended up tossing a lot of Crichton's plot and characters, though they kept a handful of key scenes, including the central set piece of mom-and-dad Tyrannosaurus Rexes attacking a trailer in order to rescue their wounded infant.

3. The little girl attacked by tiny dinosaurs in the opening scene (above) is played by Camilla Belle. She and Vanessa Lee Chester (who played Malcolm's daughter, Kelly) had both played supporting roles in Alfonso Cuarón's "A Little Princess." Fittingly, Belle would grow up to star in prehistoric adventure "10,000 B.C."

4. Early in the film, while Goldblum rides the subway, you can see a familiar-looking young man reading a newspaper. That's future "Inglourious Basterds" co-star and "Hostel" director Eli Roth, who was an extra in several movies at the dawn of his Hollywood career.

5. Koepp got the names for characters Roland (Pete Postlethwaite, above) and Van Owen (Vince Vaughn) from the macho rivals in one of his favorite songs, Warren Zevon's "Roland the Headless Thompson Gunner."

6. Vaughn was all but unknown when Spielberg cast him. The director had first noticed him while watching a pre-release edit of "Swingers," whose makers had passed it along to Spielberg in order to get his approval to borrow the "Jaws" theme music. Vaughn would also co-star in 1997 indie drama "The Locusts" with Kate Capshaw (Spielberg's wife) before "Lost World" introduced him to a mass audience.

7. While many shots in the film make use of advances in CGI that had occurred in the four years since "Jurassic Park," close-up shots of menacing carnivores were accomplished as before, with animatronic creatures built by monster-effects wizard Stan Winston.

8. The two T-Rex parents he built were so massive (19,000 pounds each -- and they were just head-and-torso) that they couldn't leave the soundstage, and sets had to be built around them. They were mounted on carts that ran on fixed tracks.

9. The crew had the most fun staging the T-Rex tracks' attack on the trailer, creature designer Shane Mahan recalled.

"At first, we were hesitant, thinking that we had to be careful with the rigs. But it got to the point where we were just, 'Ah, to hell with it,' and we just demolished that trailer with the T-Rex rigs," Mahan said. "That scene wasn't faked. Those T-Rexes were really slamming into that thing, breaking glass and shaking it. I think the scene really works because we went for it like that. You can tell that something truly violent is happening."

10. The cliff over which the damaged trailer dangles was built out of a parking garage on the Universal Studios lot.

11. Most of the outdoor footage was shot in the redwood forests of Northern California. Yeah, in real life, there are no redwood forests in Costa Rica, but the ancient, enormous trees gave the scenes the prehistoric look that Spielberg wanted.

12. The sequence where velociraptors attack in the tall grass had to be planned a year in advance, in order for the seed sown by the production crew to grow tall enough. The crew planted eight full acres, in case scenes required multiple takes, since the grass, once trampled, wouldn't spring back up.

13. The screenplay's original ending had the humans fleeing the island in helicopters while being attacked by pteranodons, but the flying lizards wouldn't get their due on screen until "Jurassic Park III." 14. The idea of ending the movie with a T-Rex attacking San Diego came from Conan Doyle's novel, whose finale brought a pterodactyl to London, and from Spielberg's delight at the idea of making his own little "Godzilla" movie and seeing a T-Rex drinking from a swimming pool.

15. How did the crew of the ship get eaten if the T-Rex was still locked in the cargo hold? Apparently, there was supposed to be a scene showing raptors aboard the ship, but it was never filmed.

16. The "Godzilla" gag isn't at all subtle, except for the fact that one of the fleeing Japanese businessmen is saying, in Japanese, "I moved from Tokyo to get away from all this!" At least the filmmakers dropped their early idea of printing out that punchline in subtitles.

17. Koepp (above) has a cameo as "Unlucky Bastard," who is eaten by the runaway T-Rex during the San Diego sequence.

18. We still get a kick out of those blink-and-you'll-miss-'em posters for imaginary movies in the San Diego video store: Tom Hanks riding a surfboard in something called "Tsunami Sunrise," a giant Robin Williams holding a tiny family in his palm in "Jack and the Beanstalks" (a hint toward the "BFG" adaptation in Spielberg's future?), and Arnold Schwarzenegger in Shakespeare's "King Lear."

19. The budget of "Lost World" was reportedly $73 million, just $8 million more than "Jurassic Park" had cost in 1993.

20. "Lost World" set box office records when it opened. Its $72.1 million opening weekend was the biggest ever at the time and held the record until "Harry Potter and the Sorcerer's Stone" surpassed it four and a half years later. It was also the fastest film to cross the $100 million mark, doing so in just six days. It ultimately earned less over the course of its run than "Jurassic Park," racking up $229 million in North America and $619 million worldwide. Still, it remained the top grossing movie for most of 1997, until "Titanic" opened in December.

21. It's no wonder Spielberg followed "Lost World" with dialogue-heavy dramas "Amistad" and "Saving Private Ryan." "It made me wistful about doing a talking picture because sometimes I got the feeling I was just making this big silent-roar movie," he said of "Lost World." "I found myself saying, 'Is that all there is? It's not enough for me.'"