Here’s the relevant exchange.
The funny thing about the transparent aluminum was that it existed even when the movie was made. Ridiculously expensive though.
I don’t think you could enclose the whales in a “sealed” container. Wouldn’t they suffocate?
Having an “open top” container might make it easier to recycle the air for the whales benefit.
Maybe Spock thought the whales need to “see out”, as well. Being put into a plain metal box might scare them too much, and they won’t respond to the probe on our behalf, at least favorably. 
Transparent aluminum does not exist, and there’s no reason to think it can exist. Transparent alumina, that is to say aluminum oxide, does exist, and is better known as sapphire.
I always wondered why they were beamed from the hospital to outside the Bird of Prey, and then they had to go up the ramp to get in, except Kirk who was then beamed into the ship. Wouldn’t it have been easier to just beam them all from the hospital into the ship?
No one has brought up the fact that the bridge of the Bird of Prey is entirely different in IV than it was when Kruge commanded it in III. He sat up above his crew on something like a dais, and his crew were all around below him. In IV it turns into a replica of a standard Constitution Class starship bridge with Kirk’s crew in the same positions they are always in.
Also, they left a phaser and a communicator behind (Chekov’s). Oopsie.
I like the way Kirk carries the pizza - under his arm like a book. He clearly doesn’t know what a pizza is and that you don’t carry them sideways. I thought it was a nice touch. Although, slight plot hole, the waiter brings it already boxed up before he knows they’re leaving.
This is also my favorite ST movie.
I made that mistake once in college, carrying a pizza from the dorm lobby back to my room.
I really wished I hadn’t 
Obviously they were trying to use that to set up a new movie. Chekov’s Gun is always a setup for something later on.
groan
Good gad, I believed you to be above such things!
Dammit, I wish I’d thought of that…
Exactly my point. It’s a puzzlement and a contradiction that bothers me every time I watch this movie.
not really that much of a puzzlement - they were trying to limit Gillian’s exposure to the future technology, and they couldn’t beam part of the party one place and the rest somewhere else.
What happened to her truck?
ETA - nm - my memory is flaky - she had already been on board (Kirk beamed her up) and given the grand tour.
You see, either when I read about or watched the scene with Scotty, I got the idea that transparent aluminum didn’t exist, and that Scotty had just given him an impossible formula that would never work. Did transparent aluminum exist in the Trek universe before that scene?
I mean, I know it’s used on the Enterprise-D in everything that appears to be glass (as an excuse for why it doesn’t break in space, but that’s TNG. Could that have possibly been the intent, at least, in an earlier draft? Or did that show up in any novelization or even TV edit?
They were part of the New York Employees exchange program, first documented in “The Critic.” There’s a bunch of cab drivers in Baghdad that were all imported from Queens, and vice versa.
It clearly existed in Scotty’s time frame -
“normally, I’d do it with a piece of transparent aluminum”
Oh I’m sure it was towed immediately, since as I said in the OP she drove down a footpath and parked where vehicles are restricted.
Seriously, the whole GGP scenes were hilarious. No people anywhere jogging or walking or playing sports or walking a dog, nobody using that field to play softball or throw the ball for their dog and running into the cloaked ship…nobody being curious about a hovering helicopter lowering a large vanishing piece of glass! In reality that would have the Park Police all over them in seconds - this isn’t some underused park in the middle of nowhere - from my living room window I would have walked over there to see what was going on with that helicopter.
I agree. The whales were already used to being in an aquarium and it would make sense to replicate that environment as much as possible. As it turned out, it did allow them to see at least one familiar face, though that could have been achieved with an accessible surface:
SCOTTY: (to Gillian) The beasties seem happy to see you, Doctor.
Its existence seemed to be implied in this conversation:
McCoy: You realize that by giving him the formula you’re altering the future.
Scotty: *Why? How do we know he didn’t invent the thing? *
There was at least one other reference to transparent aluminum prior to ST IV, though for the life of me, I can’t remember where. I’m pretty sure it wasn’t in TOS, which would put it either in the animated series or in one of the first three TREK films.
I doubt it was in any of the TREK novels, which I studiously avoid as a rule (the sole exceptions being Roddenberry’s novelization of ST: TMP and Fontana’s TOS prequel), though it could have been in one of Gerrold’s books in the early '70s.
AHEM! :dubious: