Microwave emitter, Tumbler and batpod, memory cloth, sonar equipped phones that map the entire city. I think a gun that pumps jets of liquid nitrogen is gonna be okay.
The reserves of liquid nitrogen that gun should have would have to be so huge that one person alone wouldn't be able to carry it. The cooling devices needed to kep it below 77k (-321ºF) would be too large for one person to carry. Not to mention the "Leidenfrost effect", from Wikipedia: "Despite its reputation, liquid nitrogen's as coolant is reduced by the fact that it boils inmediately on contact with a warmer object, enveloping the object in insulating nitrogen gas." (that is, hotter than its boling point, in this case -321ºF, shich should be... uh, everything out there).
So, my friend, shooting it is not an option.
I couldn't say the same thing about Tumbler, Batpod or the sonar (microwave emitter had a big hole, though, I can't deny it).
I know some of you have read this before but we have a lot of new posters now so here we go again. I wrote this at a time when people were complaining that every Freeze story was basically the same; he whinges about his wife and then zaps people, and it was getting boring. Here's my idea for a Nolan Freeze that would be pretty damn grim and bring out the best of his story. He doesn't have to be a one-note character crying over the death of his wife...
Just for argument's sake, the same can be said about virtually everycharacter out there in the comics. The wife thing and his reactions to it, the way he handles his tragedy and how focused, cold and determing he seems to be with everything except her, is what makes the character so compelling. It's not one-dimensional. His behaviour with his wife is a very contradictory element for him, because he is a guy we can all relate too, and yet see he's doing the wrong things for the right reasons, and that can't be said of other villains like, say, Two-Face. That's is precisely the opposite of 1D.
Just for argument's sake.
... instead, make him a relatively normal guy conflicted over the horrible things he has to do to save her. His wife is in an illegal and experimental cryo-stasis, however in this version it's a dingy clandestine bunker instead of some nice shiny hi-tech lab. A cure for her disease is now available.... but because the cryo-process was imperfect he doesn't know how to bring her out without leaving brain damage. He needs to experiment on other living patients, and he needs a steady supply.
The scientist makes a deal with a criminal enterprise to dispose of their mob victims as long as they're delivered to him alive. Maybe the mob try to blackmail him into it when they discover his secret bunker or something. Either way, it's mutually beneficial; when the 'experiments' eventually become corpses the freezing process will confuse police examiners to the time of death, thwarting investigation.
Okay, not so bad idea except that I don't buy the bunker thing (what's the point of it? bringing something different? I think it is completely gratituous and there's a lot to explain about it. the high tech lab thing AT LEAST makes a commentary of how ruthless the world of science/health industry can get.)
And... why would the mob start sparing their victim's life to get them to Freeze? Do you know what the logistics of that would be? The mob kills because it's easy, it's quick, it's cheap. To go the other way around just to confuse the medical examiners is... (yeah, you know it)... forced upon and gratituous. I believe you can do better than this.
IF Freeze does it in the spot, and then becomes a hitman, and IF he does it with a cold gun.... I can understand. If.
Of course you don't need me to understand because it's fun and it seems good in you head. I'm just saying: good idea... holes in it... can be improved.
So now you've got a terrified and desperate scientist freezing people alive in a dark little basement and ultimately committing murder for his wife. He's tortured by it but he has no choice. Eventually the mob boss decides the scientist will probably collapse under the strain of such depravity and confess to the police, so he sends hitmen along to get him. But the scientist is as clever as he is paranoid, and the hitmen never return. He devices a weapon to fend of the inevitable reprisals that will follow.
What about the one-note wife whining thing? Apart from the bunker (which can be traced to the comics too) you're not changing a thing. I'm a little confused here. Paul Dini would be proud.
The reason he uses this special 'Liquid Ice' pump is because it doesn't kill on contact.
Oh, no, ut just causes severe frostbite. And, of course, you can't shoot it because of the Leidenfrost effect. Nope, it's no easy thing to be Fries.
Victims become slow and collapse into a frozen unconsciousness, thus preserving them for experiments. Previously on the first attack against the hitmen the scientist used regular dry ice, the kind that exists in the real world. This stuff is deadly, it kills on contact so it's no good. At this point he needs to go out and proactively target his enemies instead of waiting for them to send hitmen to his bunker, endangering the safety of his wife. He'll wipe them out until they agree to leave him alone, but while he's killing them he may as well get paid for it...so here's the opportunity for an alliance with a rival mob. The desperate scientist becomes reluctant assassin: he doesn't doesn't belong in this seedy world and it begins to eat his soul. Also, he knows not to make the same mistake twice in dealing with the mob....to preserve his identity among his new cohorts he wears a full body thermal suit, the same one he wears to keep warm when working in his refrigerated bunker. He looks like a ghostly spaceman, and they dub him "Mr.Freeze".
To preserve his identity he wears a HEAVY, unconfortable thermal suit. instead of an old plain mask? Why? Just to make his "it's a small step to man" routine?
Nop, not an easy thing to be Fries.
When Batman eventually clues his way to Freeze's bunker he's attacked by mindless, vicious freeze-zombies!
Ho ho, Nolan wold be so thrilled to read this.

Freeze-zombies, hahaha. No, I think you're thinking about Francis Lawrence to direct this.
They're the brain damaged survivors of the process who are now subservient to the scientist.
Ohhhh, sweet Jesus.
He encases Batman in a layer of ice, his ruined armour protects him but he's numb, slow and clumsy, making it hard to avoid blows from an icepick. Freeze tries to apologise for what he's doing, crying as he lays on blows. When he's finally sent to Blackgate Bruce Wayne pays for an in-house cryolab so the repentant scientist can continue researching how to save his wife, along with the victims that are still frozen alive.
And what have I learned from this? A good, true to the source final paragraph... does NOT redeem freeze-zombies.
Yeah, alright, you and Schumacher have convinced me... Freeze can't be done in the movies. Well, I'l start pushing for another villain. Thanks for making me realize I was wasting my time with this character.
p.s. Reading that above, I even got to miss Schumacher's ice-skaters.
Nah, just kidding
... or not?