I worked for the theme park inside the Mall of America as a ride operator for several years back in the early aughts. I cannot speak for other theme parks, but for that one I can tell you that the rides at the one I worked at were/are really safe. They all had fairly state of the art hydraulic systems that were/are routinely maintained.
The larger rides are run through several safety tests first thing in the morning before the park opens, and certain large rides like the log ride and the roller coasters are actually ridden by park supervisors each day before they're allowed to be opened.
Probably 98% of the time, the injuries we did have to deal with were the direct result of parents either not supervising their children or actively encouraging their kids to break the rules.
The children themselves were usually on their best behavior because they knew that I could remove them from the ride if they broke the rules, but the parenting at theme parks is abysmal. I have sooooooooo many stories of parents putting their children in harm's way on purpose. I could do a whole AMA just on that topic.
The worst mechanical malfunction I ever had was on a ride that I believe no longer exists there called The Might Axe. It made the news in the 90's for getting stuck upside down and the fire department had to cut everyone out.
What the news media left out was that the maintenance department could've gotten everyone down in 10 minutes, but people called 911 from their phones and the fire department overruled the maitenance guys and spent 2 hours cutting everyone out of their seat restraints, which cost the theme park a ton of money to fix.
I wasn't working at the park when that happened, but afterwards there were strict guidelines put in place for when it did get stuck. During my tenure at the park I got assigned to that ride rotation a lot and had The Mighty Axe get stuck upside down twice.
Both times maintenance was able to fix the problem pretty swiftly, but it would result in people trying to call 911 every time, which was very annoying.
The worst was watching people try to wriggle out of their seat restraints WHILE UPSIDE DOWN because they apparently thought it would be a great idea to try to get loose and then fall 2 stories into a concrete pit. People are remarkably stupid.
We had a rip tide water ride where people could ride body boards like a big wave and while I was talking to another guard I heard the whistle go off like there was an emergency.
As I approached, a guard told me that there was a nail in someones foot.
I thought he meant someone stubbed their toe and their nail pushed back into their toe but it was an 8 year old girl who had stepped on a 4 inch screw leftover from the maintenence the ride had recently undergone. Right into the heel.
As I saw it i got a little light headed but that what I was trained to do so as i picked her up and pulled her out of the water she moved her foot and it started to come out but it was still in there a good 3 inches.
I put a latex glove on it and told her itd be ok as I called for paramedics.
Her damn brothers came up and said that she was gonna ruin their time if they had to leave and i had to tell them to get away.
When the paramedics came they picked her up to put her on the stretcher and when they did,
that good ol latex glove slid off her foot and got hooked on the screw in the foot causing her, what I believed by her screams, excruciating pain.
Never found out what happened after that but she should have sued. Big payday.
I used to work at a small water park where there were some dry rides up the southern end. There was this 8-year old kid just being a little s**t; pushing in line, climbing up the slide of the playground, knocking other kid's hats off, that sort of bullshit. I warn him several times then ask him to leave, but he doesn't.
I go and ask my supervisor what to do and he says "Get the scissors". He means to cut his wristband, without which he can't go on any rides. I call him over, and he surprisingly complies, and before he can react, I grab his wrist and cut off his wristband.
Naturally, he starts crying like a b***h. He runs off to get his mum and she comes back about 15 minutes later and comes and talks to me (without her son).
She asks why I did what I did, and I explain the situation to her, and how it is standard procedure.
She nods and understands, and knows that her son is a demon-child. She leaves, but, lo and behold, 10 minutes later here he comes.
He tries to cut in line again and I stop him, and ask him to go back to his mum. His first reaction was to punch me in the balls. Oh s**t, no he didn't. My supervisor sees and immediately calls security.
Apparently his mum saw too and she comes running. She doesn't say anything to her child, but goes and tells the supervisor to 'scare' him. When security arrives (30 seconds later) they grab the kid, whirl him around and handcuff him.
He's s**tting himself at this point. They grab him and take him off in their golf cart.
A few minutes later they return and the kid has obviously been crying, and hard. He jumps out of the cart and runs straight to his mum, who grabs him and walks out. People watching were stunned, but amazingly, and I shit you not, some applauded as they went off. Best day of work I had at that place.
Some (mutter mutter) years ago, I was working my summer vacation at an amusement park, running a rollercoaster. I got to sit and push buttons, give the safety instructions, etc.
So, we get the train full of people, I get the all clear, hit the button to start the train up the hill, when I see something out of my periphery. A guy has somehow climbed the gigantic wall surrounding the ride, and has dropped down next to the track, where I am about to send a metal train full of people at 40 mph. I slam on the emergency stop button, which shuts down everything on the ride, and grab the phone for security.
My coworkers come up to see what's happening, and I point to the guy down in the ride zone. He's acting weird and erratic, and is actually climbing on the rollercoaster's track, and is taking off his clothes. Security tells us not to approach him, in case he's dangerous, and to move the people in line away.
Meanwhile, I head up the stairs to talk to the people who are stuck in the ride. The stairs were open, metal things, extra narrow, steep, and at this point, damp. In the best of times, I hated climbing them.
I get up and most of the people are calm, except for one woman who is freaking out. She's panicking that the ride is malfunctioning, and that she wants off.
Now, I understand panic attacks and how you're completely slave to them. So, I'm calmly telling everyone that I was the person who hit the emergency stop, why I did it, etc. From their viewpoint, they literally could see the guy climbing up the track, security chasing after him, etc. I've called for a manager to let this lady off because I'm not able to do it.
So, the manager finally arrives, lets this woman off with dire warnings about how dangerous the steps can be. By this point, the police are arriving, there's all sorts of stuff going on in the sights of the patrons as they are trying to arrest this guy.
And then, a guy on the ride announces he wants off too. So, the manager lets him off. He climbs over another guest, faces the train, and calmly announces that this entire thing--the half naked man, security, the police-- all of it was just a cover up for the fact that the ride had malfunctioned and that they were all going to die.
And I'll be damned if they didn't believe him. We evacuated that ride, and two people slipped walking down those stairs. I had to fill out massive paperwork to keep people from suing, thankfully we were able to call a cop over to witness. After police left, the ride was started back up, with no issues.