It seems like Gaff speaks almost no English at the beginning of the movie, but has become conversant by the end. Is this deliberate? Why?
In one of the first scenes, Captain Bryant has sent Gaff (Edward James Olmos) to bring Deckard (Harrison Ford) to him. Gaff finds Deckard eating noodles, and begins speaking to him in a language other than English. Deckard does not understand him, and summons the elderly chef to translate, who shares that Gaff is attempting to place Deckard under arrest. Gaff eventually gets out the word "Bryant," which convinces Deckard to go with him.
Fast-forward about 2 hours to the scene where Deckard and Roy Batty are on the roof of JF Sebastian's dilapidated hotel. Gaff lands his police cruiser on the roof, and shouts to Deckard:
You've done a man's job, sir. I guess you're through, huh? It's too bad she won't live. But then again, who does?
I don't know how much time is supposed to elapse between those two moments, but it seems like it can't be more than a few days, perhaps a week. At the beginning of that week, this police officer cannot even say "you're under arrest" in English. At the end of that week, the same officer seems plenty fluent.
How can that be? Humans generally cannot gain language proficiency with anything like that speed.
Perhaps you're thinking: Gaff hasn't really learned English, he's only memorized a couple of statements. (Nevermind how he knew in advance what statements would be appropriate when he finally caught up with Deckard.) If that's the case, then why wouldn't he also know how to say bread-and-butter police stuff like "you're under arrest," or "get in the car?"
Is the implication that Gaff is a Replicant? Or is this a pair of identical twins who both work for Bryant, only one being fluent in English?