Are they? They call it a proton river not an anti-proton river.
So I saw it yesterday night and they said anti-proton river a couple of times, but they didn't say proton river that I heard.
However those scenes are not exactly quiet, and there's a lost going on sonically, so it's quite likely the "anti" part got lost in the mix in a lot of theatre sound systems (especially in the UK was we tend sadly, to exceptionally poor movie theatre sound mixing in perhaps the majority of non-indie, non-IMAX theatres).
Y'all know how picky I am about this kind of thing so I'm pretty confident my awful brain would have leapt on any inconsistency of usage here. Certainly the first time it's mentioned, by Mr Terrific to Lois, he describes it as an "anti-proton river", and I was struck by this because antimatter is alarming!
Re: the movie in general:
I really liked it, it was better than I expected and stranger too. I really didn't anticipate it being such a Krypto movie! WHAT A GOOD BOY!!! (Also a very naughty boy but we don't tell him that!) I really liked that though! I liked that Superman's main motivation for going to this weird realm was "I need to get the awful dog back!". That's legit. That's relatable. Superman being like, actually good - caring about kids and animals and stuff was genuinely refreshing. Also what a way to defeat Luthor - naughty dog behaviour saves the Earth!
As ever with Gunn, he was able to make almost all the characters work emotionally, even ones who were on screen for a relatively short time. He's very good at handling ensembles and he just keeps showing that over and over.
I thought the weakest point here was Lex Luthor. Not because he wasn't played well (some of the line deliveries were glorious), but I didn't think his rationale was as well-constructed as it could have been, and I didn't think he was as compelling as a villain as he could have been as a result, nor did Superman's speech to him at the end quite land for me because again, I don't think his motivation was exactly believable. It was like Gunn had taken a believable motivation and then just overcomplicated it, in part by having Luthor understand himself too well. But that wasn't much of a weak point!
Really kind of want a Mr Terrific movie or show now! Honestly his fight scene might actually have been better than any of Supes' fight scenes (strong shades of the the arrow scene from GotG2). Also maaaaaan Edi Gathegi looking incredible in that costume - very rare that someone looks hotter in a modern superhero movie costume than "civilian clothes" but wow the cut on that.
Also Jimmy stop being mean to Eve she's so nice and so out-of-your-league! (I appreciate they acknowledged this with Lois' perplexed "How do you do it?" comment)!
As an aside: my (19 year old_ daughter was FURIOUS at the brief depiction of Supergirl. She loves the Melissa Benoist version of the character and was extremely put off by the "party girl" version.
I kind of share your daughter's concerns here. I don't like, hate the idea of "Party Girl Supergirl" as a pure concept, but I feel like Supergirl is a fairly defined character a lot of people like and having her be a "party girl" (rather than a very good girl) suddenly is not entirely unlike having Superman be a jerk (as per the Snyderverse). I guess it's a starting point for a character arc, and a differentiator from Supes earnestness, but I'll be interested to see if Gunn etc. can make that compelling, especially with Milly Alcock in the role (who generally seems drawn to rather sour characters). Given that this bastard managed to make me LIKE PEACEMAKER after making me utterly loathe every fibre of his being in The Suicide Squad, I'm going with probably yes if Gunn himself is writing/directing but still.
So one thing did surprise me - Superman's Kryptonian parents being evil! Is that like, common in DC lore? I was under the impression from all the previous Superman stuff I'd seen and read that they were basically good and wanted him to do good, but this movie seemed fairly insistent that they wanted Superman to be benevolent dynasty-founding God-Emperor of Earth in a very Omni-Man kind of way, and that there was no mistake about that, which would generally make them very bad people. I don't hate it but it did surprise me.