There's a lot of detail written into the first part of the scene. From where the clip starts, it's not evident if there was a cat there or not (and it's been a long time since I've seen the movie). We do get a person in the early part, the dump-truck driver, who gives an appropriate reaction to what's going on which is probably a heck of a lot easier to film than a cat. There is also no lightning storm across the city, something that would have been hard to predict. The following scene with the punks may have come into question as a result: I don't know if too many people who hang around outside when a storm's brewing. In the storm's place, the punks are using a telescope. This makes me wonder if the shooting location ended up dictating the elements in the scene. As such, they wouldn't have been using said telescope had their been a storm (they're not THAT stupid, are they?). A subtle difference once we see the Terminator is he's sort of like the honey badger in that he doesn't give a shit - so the part of him surveying and dusting himself off was changed. There is no vanity in Terminators! There's some additional dialogue when we first see the punks, more or less characterizing them (punks will be punks) and giving a hint of unpredictability to them. "A couple of bricks short" has been changed to make it more relevant, perhaps, to their drinking... but a couple of bricks short of what anyway? The punks draw their knives when threatened because, well, that's what punks do, right? Again, I think it goes to show them as being a bit menacing themselves. It's a good comparison to the intro of Once Upon a Time in the West: the scene and subsequent encounters don't have the impact if there's no suspense and having an air of unpredictability and malice help create this in both instances. If the punks weren't badass punks and the outlaws weren't badass outlaws, the tension and suspense within the scene wouldn't be anywhere near as strong. One of the punks also manages to strike the honey badger, er, Terminator, who just doesn't care. It's another way of demonstrating his otherworldliness and gives us something to hang tension of future encounters of off. As we all know, Terminator goes through one heck of a ride in the film, ending up a scrap heap. The knifing here is just a prelude of things to come.

The major difference is the change in location. Instead of a school, the scene takes place at Griffith Observatory in Los Angeles (of Rebel Without a Cause fame), which is perfect because it overlooks the city exactly as the script demands. As The Bark Bites Back noted, there is a truck driver instead of a cat. In fact, it's a dump truck instead of a dumpster in the scene. And as noted, having the first reaction of the lightening storm of the Terminator's arrival come from a person is better than coming from a cat. To me, one of the most important reasons to reads scripts is to see how other writers describe things, and add those words and phrases you wouldn't normally use to your lexicon. Here are some of descriptions that I wouldn't have thought to use: like a Jacob's Ladder embankment promontory malign good humor hammer-punches piledriver force