Predator - "Nothing like it has ever been on Earth before"
Predator 2 - The Elder has a Flint lock pistol from 1715. Unless that Predator ransacked an antique shop, that means the Preds HAVE BEEN to Earth before.
Predator - While wearing it's Bio the Predator sees with thermal vision. Once the Bio is removed (actually WHILE it's being removed) you see the visual spectrum change from thermal to a completely red view. Meaning THAT'S the normal vision of a Predator.
Predator 2 - This Pred sees with thermal vision just like the first hunter, except it's revealed that the bio actually allows MORE visual spectrums (you see the Pred cycle through them in the meat warehouse). Problem is, once this Predator's Bio is removed by Harrigan, and AFTER the Predator smashes Harrigan's shotgun, you see a shot from the Preds POV (without a Bio on) of Keyes and it's in THERMAL VISION.. not the complete red spectrum from the first movie. Obviously it's an editing error.. but since it's in the film it's cannon and a plot hole.
Predator - There's at least one scene of the Predator sitting high up in the trees admiring his skull trophies (some from Harper and his team, some from Dutch's team) and they're all completely cleaned and polished.
Predator 2 - In Predator 2 when the Hunter kills King Willie, it takes Willie's severed head BACK to it's ship, and cleans/polishes it THERE. On that SHIP.
Everyone here says the first Pred came to Earth in a Pod just like in AVP/AVP:R. From what we've seen in AVP and AVP:R the pods are disposable once the Preds leave them. There isn't a single scene (deleted or otherwise) of a Predator in AVP and AVP:R returning to one of those pods. So their only use is for a one way trip to a destination. If the first Predator had no ship like everyone here claims, what did he polish his skull trophies with? There isn't a single scene in Predator explaining that. But it IS explained in P2 with the scene of the Predator cleaning/polishing King Willies skull. INSIDE A SHIP.
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The above answers are all WITHIN the movie. What I'm about to say now is OUTSIDE of the movie. So it's a "Real Life" answer/explanation.
Source: "Hunter" Script (the original title and script for Predator)
Dutch (Originally called Schaefer)
SCHAEFER
(incredulous)
Who the hell are you...?
EXT. HUNTER'S P.O.V. OF SCHAEFER - NIGHT
Schaefer's body, looms over him, MOTTLED and STREAKED
from his exposed skin, blood oozing from the shoulder
wound, his eyes like black sockets in his almost
skull-like face. Seen from this perspective, Schaefer
is a frightening, horrible visage.
THE HUNTER
shudders, GASPING hungrily for air, strugging to speak.
From his throat, Schaefer HEARS the feeble, distorted
efforts of the Hunter, at first garbled,
incomprehensible and then, slowly, chillingly, taking
on the timbre and quality of his OWN VOICE.
HUNTER
(electronic;
filtered)
Who...
(improving)
...the hell...
(nearly perfect)
...are...
(perfect)
...You?
No mention in the script of the Predator simply "mimicing" at that point.
He turns back, SEEING the Hunter as he passes through
the shimmering distortion of a FORCEFIELD enveloping
the forest. Within the force field he SEES the vague,
nearly transparent OUTLINE of the Hunter's ship.
He approaches it, wide-eyed, his senses reeling with
astonishment and rage.
From within the force field, a PASSAGE WAY of BLUE LIGHT
appears, the Hunter's form backlit as he ascends the
RAMP to his spacecraft.
THE HUNTER
as he passes his hand through a light BEAM, the ship
instantly responds, as a low, TURBINELIKE HOWL is
HEARD, building slowly in volume and pitch.
SCHAEFER
in his weakened condition staggers forward, looking
up, SEEING the passage way of light diminish as the
door begins to close.
As rising HEAT WAVES begin to envelope the ship, the
Hunter stares out at Schaefer, the heat waves
increasing as the KEENING WHINE of the ship's drive
builds. He enters the force field, the door now
inches from closing.
Obviously all of this was changed. But as you can see in the original story the First Predator came to Earth in a SHIP.
