WMG / Jurassic Park III

Billy dies soon after the end of the film
He's seen drinking directly from a stream while telling the Kirbys that Grant was probably headed for the coast. Anyone with even relatively little survival skills knows that this is the best way to kill yourself in the wild, and he almost definitely got sick on the way home or upon arrival. The massive amount of injuries he sustained almost certainly didn't help his condition.
  • A person may get sick from drinking stream water, but in a survival situation, it is far better than nothing. Depending on the location, it is not uncommon for casual hikers to drink from stream water.
Nash's Satellite Phone was Made of Indestructium and had nuclear batteries
Keep in mind: The Spinosaurus ate Nash, he chewed him, then he digested him. When they found the phone in a pile of poo, keep in mind that Nash bones weren't seen: A Phone, which is supposedly made of plastic, and a few pieces of metal and silicium, endures the bites, the acids and antacids better than BONES. Also, I don't know yours, but my cell phone battery doesn't last for a lot of time, mostly if it's receiving calls, and has a loud ringtone. The only explanation is, effectively, that it's really Made Of Indestructium.
  • Perhaps it's a Nokia?
The Pteranodons were made with bird DNA.
It's been a long time since I've seen the JP franchise, but IIRC, InGen used amphibian and reptile DNA as part of their dino reconstructions. Now obviously, they couldn't rely on reptiles and amphibians alone with the pterosaurs; after all, frogs and lizards can't fly.

Their solution? Simple, use the DNA of birds and mix those in with the pterosaur, amphibian and reptile DNA. Essentially, they had invoked All Flyers Are Birds.
  • While lizards and frogs can't fly, pterosaurs certainly could. Why did they need to introduce the DNA of other flying creatures to get the Pteranodon off the ground? Birds, bats and pterosaurs are the three flying vertebrates.
  • That's something I never considered. Perhaps instead, the bird DNA was added as a supplement or to make the pterosaurs live up to the expectations of park goers. Either way, bird DNA would be the perfect explanation for their decidedly birdlike behavior.
  • Bird DNA could have just as easily been the filler DNA used in pteranodon production instead of frog DNA.
The raptors are going to start their own civilization at this rate.
And it will be glorious.

The T. rex that fights the spinosaurus was the injured baby from The Lost World: Jurassic Park.
This was actually confirmed by Joe Johnston. Don't worry, T. rex fans. You can cling to the idea that the Spino only killed a young rex with a possibly defective leg going back to its injury in the second movie.
  • Jossed. The creators were actually joking when they "confirmed" it was the baby.
  • While it almost certainly isn't the baby, it is the smallest adult rex in the series by far. So it perhaps wasn't quite fully grown, or was the runt of its litter.

The Spinosaurus is one of InGen's early bioweapon projects.
There's a throwaway line early on with Allan and Billy pointing out that the Spinosaurus isn't on InGen's list of cloned dinosaurs with the two of them wondering what the company was up to. In fact, the Spinosaurus was one of InGen's first attempts at producing a weaponized dinosaur hybrid, which explains many of the traits, like its persistent pursuit of the human protagonists (despite them being less than optimal prey), its exaggerated predatory nature (bigger and meaner than a T.rex), traits that it shares with the antagonist of Jurassic World, and why it wasn't on the original list of dinosaurs that InGen supplied. This was probably meant to be foreshadowing that would have lead into the fourth film before it got trapped in Development Hell for a decade. The Spinosaurus is basically the conceptual prototype for the I. rex.
  • Confirmed. Wu himself considered it as accident. The accident was because the spinosaurus turned out to be too stupid to be a weapon. This creature's aggression, compulsive need to kill every human on sight, destruction of anything in its way and supernatural power have all being created to be a bioweapon. No attraction dinosaur would have these features.

The Spinosaurus is a early experiment for Jurassic Park
Think about it all of the dinosaurs from the first three films can from from the DNA found inside of a fossilized mosquito trapped in amber. This means that the scientists doing all of the genetic work would not know the exact type of animal they're cloning until one has already been cloned, giving the scientists something to compare it to. Naturally the Spinosaurus ended up being a failure and did not end up in Jurassic Park, which is why it wasn't on the list.

The Spinosaurus was the precursor of the I. Rex.
Some genetic experimentation occurred behind Hammond's back. It failed, and the Spinosaurus was released on Sorna and forgotten about. This is why it hates humans and how it beat the T. Rex.

  • Maybe that was why it didn't crash through a locked door. It was trained not to.
    • Confirmed, sort of. It has been revealed (or at least heavily implied) on the Jurassic World website that the Spinosaurus was one of Wu's first serious forays into genetic hybridization. Although not nessesarily a purposeful precursor to the Indominus, it was what showed him the potential power of the process, and likely inspired him.

The T. Rex couple from The Lost World: Jurassic Park killed the Spinosaurus.
Some time after the events of the movie, the Spinosaurus attacked the T. Rex couple in an attempt to claim their territory for itself. Unfortunately for it, this T. Rex duo is far, far deadlier than the last one it killed, not to mention that they outnumber it. As a result, the Spinosaurus looses this one rather quickly.
  • Partly confirmed. The Spinosaurus is confirmed to be dead, but the reason isn't clear. However, it's very likely that the T-Rex couple did it.

Grant had mentioned to Ellie that he was giving the tour over Isla Sorna
It Explains fully how she knew where he was and what kind of trouble he was in

The Spinosaurus is a hybrid of...
Actual Spinosaurus, Tyrannosaurus, and Suchomimus. It's been all but confirmed that the Spino is an early hybrid dinosaur like the Indominus. Its base genome was Spinosaurus, but it had a Suchomimus like head. It got its body proportions, great strength , and aggression from T. rex.