I love action-y sci-fi movies (and games, for that matter. A lot of this applies to them too) so that's the genre this list is focused on. That said, plenty of these points can be applied to other genres and media too.
Finally, standard internet disclaimer: yes, I'm aware there are exceptions to all of these. Yes, there are problems with how men are depicted in the media too. No, I'm not some joyless harpy or prude who's opposed to all sexiness/nudity or even objectification in all contexts.
So, here goes:
1. When an otherwise badass, capable female character is suddenly and uncharacteristically overwhelmed and needs to be rescued by the male protagonist. Now obviously there are cases where this is appropriate: she's legitimately injured, fine; she rescues him from a similar predicament at some other point in the film, ok, I'll buy it - maybe it's a way to demonstrate that they've got each other's backs. But when this sort of scene exists purely to perpetuate stereotypical gender roles - he's a big manly man of a protagonist, he must protect women because women clearly need protecting! - it seriously pisses me off. It's particularly jarring when the character in question has already proven herself perfectly capable of handling equally or more dangerous scenarios and opponents, but suddenly she's floored by one dude/alien/whatever (who, just to really emphasise the fact that she's female and therefore especially vulnerable, is probably trying to rape her). Not cool.
This is of course assuming that a woman is even included and sufficiently characterised at all:
2. All- or almost exclusively-male casts. I get it, these movies tend to be about people in stereotypically "masculine" roles (soldiers, adventurers, mercenaries, convicts... you know the drill). These fields may well be male-dominated now. But the thing is, the overwhelming majority of these stories are set in the future, and while I am aware and suportive of the fact that sci-fi can be a great vehicle for discussions of contemporary issues, that simply isn't what's going on in many of these cases. Extrapolating today's prejudices and demographics onto future settings is just lazy, especially in cases where the Token Chick (more on her later) has proved that it is possible for women to make it in these settings, and even achieve a high rank - female seconds-in-command are not particularly uncommon. Female leaders, on the other hand...
3. All-male background characters. As in number 2, would it really kill Hollywood to chuck in a few mercs/soldiers/hench(wo)men/guards/gangsters/enemies who just happen to be female? And not make a big deal out of it? Pretty please? Seriously, just have a few women there, chilling in the background with their male colleagues, even getting expendably mowed down when the time comes. That's totally ok. Anything other than the bizarre worlds we currently get where at least 95% of the population appears to be male. Seriously, do all the women get wiped out by a mysterious plague sometime around the turn of the 22nd century? Where are they all?! (Credit where it's due, I thought the Mass Effect games did a refreshingly good job of this.)
4. The Token Chick (TM). As a direct result of the general lack of women outlined in the previous two points, when a woman actually is included she far too often exists simply as "the girl." Even in films like these where characterisation can admittedly be thin on the ground, male characters, who cannot be singled out on account of their gender, will at least get to be cariacatures such as "the joker," "the naive one," "the strong leader" etc. With the Token Chick, her whole character basically boils down to "has tits and ovaries." Pro-tip, writers: gender is not a character trait. See also race and sexual orientation while we're at it.
5. The general problem of "femininity." I'm probably going to sound like I'll never be happy with this one, but what I'm really asking for is some middle-ground. At one end of the spectrum we have the butch lesbian stereotype. Now, I am well aware that butch lesbians exist, and believe me I have no problem with that. What is frustrating, however, is when this stereotype is used as an "excuse" for the character's "unfeminine" looks and/or behaviour. As in, "sure, she's a kick-ass soldier with muscles and short hair and she swears like a trooper and she's not conventionally attractive, but don't worry, dear male viewer, she's not into dudes so you don't have to want to bang her. And here's a more conventional (and conveniently straight) chick for you to enjoy. She'll probably screw the male protagonist at some point." My point is, it's way too rare for women in these settings to be "unfeminine" unless that's qualified in terms of an existing stereotype. It's for this reason that I LOVE that Vasquez isn't pigeon-holed as a butch lesbian and that it's even (*gasp*) implied that she might be romantically involved with Drake. That's right folks, turns out it might be possible for a man to appreciate an awesome, "unfeminine" woman like Vasquez. Obviously I don't want to start judging female characters on their ability to get a man (*shudder*), but it's encouraging when rare examples of non-stereotypical women being considered attractive do emerge, even if only in subtext.
The flip-side of this is when writers feel the need to lumber badass female characters with unnecessary "softer," "more feminine" sides, presumably so as not to confuse an audience that apparently can't cope without societal gender stereotypes. Motherhood/"maternal instincts" are commonly wheeled out for this purpose (looking at you, Aliens), and I just don't see why it's necessary a lot of the time. Does Vin Diesel ever need to take time out from his ass-kicking schedule to show us the deep, unshakable desire to be a daddy that proves to us that he's a "real" man? Nope, thought not. So stop doing it to female characters.
6. Inappropriate or inconsistent costumes. You knew it was coming. It's the equivalent of fantasy's much mocked but still distressingly prevalent "chainmail bikini." Far too often, female characters will be decked out in costumes that straight up don't make sense. Bared midriffs, cleavage (the chest. Where the heart lives. Just where you want a massive hole in your armour, obviously), freakin' high heels... why, exactly? None of these things make one iota of sense, particularly not if we're expected to believe that these ladies get up to any fighting on a regular basis. Why is the Token Chick the only one in a skintight bodysuit? How the hell does her hair and makeup stay so perfect throughout the movie? Scratch that, why the hell is a female marine in the middle of a warzone (for example) bothering with makeup at all?! Scratch THAT, how come this female marine, surrounded by hench manly beefcakes, is about as muscular as a coathanger? (Believe it or not, I thought Mother Russia in Kick-Ass 2 looked AWESOME). And how considerate of her enemies not to mess up her face too badly, and only leave her with a few artistically arranged and purely superficial cuts, above one eyebrow, say, or nicely highlighting a cheekbone. How is it that she's the only one whose skin actually seems to repel a quantity of the dirt and blood her male counterparts are caked in? It's almost like she exists only as decoration for the benefit of the male audience. Oh, wait...
There are others, but I'm getting tired so I'll end on one of the tackiest and most offensive tropes, one that packs the double whammy of misogyny AND homophobia, because why limit yourself to only one form of dickish behaviour? This is the one that really pissed me off about Riddick, it is (SPOILER ALERT) ...
7. The lesbian being "cured" of her penis aversion by the male protagonist. Yup. Surely I don't need to elaborate any further? It's lazy, it's crass, it's grossly offensive and it perpetuates horrible and downright damaging views of female sexuality. You can have any woman you want if you push your manliness enough! So what if she's not into dudes, all she really needs is a good fucking and you're the man to give it to her! And don't forget kids, lesbian (and bisexual) women only really exist to fulfil the fantasies of straight men! Urgh. Of all the tropes on this list, this is the one that actually makes me feel dirty for supporting the people who made the film/game/whatever and precludes me from being able to endorse it in any way, shape or form. It's a total dealbreaker, and it's disgusting that it continues to weasel its way into mainstream entertainment.
I'm sure I haven't said anything new in this note, and frankly it saddens me that these things still need to be said. However, if nothing else it's cathartic to put these frustrations into words. Here's to better things to come.