As always, the Apollo Lunar Surface Journal is a treasure trove of annotated examples. During the later (J) missions in particular, Ed Fendell, remotely operating the rover's TV camera, managed to capture a few for posterity.
Falling forward (straight or a bit to one side) happened to several moon walkers, and getting up was not that difficult. Only Charlie Duke managed to fall spectacularly onto his back pack. On that occasion, he was behind the rover seats as seen by the camera, but we hear him asking John for a hand.
Apollo 16, first EVA, Charlie Duke working on the Deep Core:
121:29:52 Duke: Uh-oh.
[Charlie has fallen and we see a spray of dust at the bottom of the TV picture.]
121:29:55 Young: Just a minute, Charlie.
121:29:56 Duke: Fell down. (Long Pause)
[John may have seen Charlie's fall and, if so, is offering to help him get up.]
[Fendell pans left to find Charlie. He is on his knees, leaning far forward with his right hand on the protruding core stem. He is trying to attach the wrench with his left hand. He seems to give up on the wrench for the moment and, in trying to get up, he lifts off his knees, pulls his feet in toward the core stem, and kneels again - all the while keeping his right hand on the core stem. Finally, he releases his grip, pushes up with his legs, and then runs forward to get his balance. In comparison with John's easy rise at 121:22:05, Charlie has expended a lot of excess energy.]
121:30:17 Duke: (Grunting) Agh! There we go.
(MPEG video) (Youtube Mirror)
121:37:04 Duke: Boy, all the sections are like that first one (meaning that the stems turn in the hole when he tries to attach the next stem). (Pause) (Thinking about extracting the core) (It feels like I could) pull it right out of the ground; but I don't think that's true. (Long Pause)
[Fendell pans left and finds Charlie threading the fourth core stem. Charlie isn't sure it's secure and drops to his knees, holding onto the drill string with his right hand. After checking the joint, he rises vertically, using the drill string to keep himself steady and, as he gets vertical, kicking his feet under himself. This is a good illustration that it is stability and not strength that is the key factor in getting up. Once up, Charlie grabs the drill.]
121:37:52 Duke: I tell you, this ain't the cleanest place I've ever been in my life. Ooh! Dust is everywhere. (Long Pause)
Apollo 16, near the end of the third EVA:
(MPEG video) (Youtube Mirror)
170:22:08 Duke: (Commenting on John's jump) About 4 feet.
[As John completes his last jump, Fendell pans left and finds Charlie, who does a short jump and then tries a big one.]
[In his book, Moonwalker, Charlie says "I decided to join in and made a big push off the moon, getting about four feet high. 'Wow!', I exclaimed. But as I straightened up, the weight of my backpack pulled me over backward. Now I was coming down on my back. I tried to correct myself but couldn't, and as my heart filled with fear I fell the four feet, hitting hard - right on my backpack. Panic! The thought that I'd die raced across my mind. It was the only time in our whole lunar stay that I had a real moment of panic and thought I had killed myself. The suit and backpack weren't designed to support a four-foot fall. Had the backpack broken or the suit split open, I would have lost my air. A rapid decompression, or as one friend calls it, a high-altitude hiss-out, and I would have been dead instantly. Fortunately, everything held together."]
170:22:08 Duke: (Doing his own jump and realizing he's going over backwards) Wow!
[In a slow-motion replay of Charlie's jump, his backward rotation is clearly visible. He may have reached a height of 0.81 meters or 2.7 feet. As he comes down, he is leaning back as much as 20-30 degrees and, although he lands on his feet, he can do nothing to stop falling backwards onto his PLSS.]
170:22:14 Young: Charlie!
170:22:15 Duke: That ain't any fun, is it?
170:22:17 Young: That ain't very smart.
170:22:18 Duke: That ain't very smart. (Apparently trying to get onto his hands and knees) Well, I'm sorry about that.
170:22:23 Young: Right. Now we do have some work to do (brushing Charlie's suit). (Pause)
170:22:32 Duke: (Apparently unable to turn over) Agh! How about a hand, John? There we go. Okay.
[Although Charlie is hidden by the Rover while he tries to get up, when John does give him a hand and he rises, it does appear that he was still facing up.]
Apollo 17, first EVA, Gene Cernan and Jack Schmitt trying to retrieve the Deep Core:
121:00:24 Cernan: Okay. Now try it. (Pause) See, if we can get a couple of inches at a throw, (then) we're all right. There you go. Do that for a little bit. (Pause)
[Jack now has his right hand on the core for balance while he literally falls forward on the handle with his left hand. He has his toes as far out behind as he can, and his knees are bent at the thirty-degree position that is built into the suit.]
[Schmitt - "I was trying to get all of my weight on the handle, just to get it to move. Gene was just heavier and could get it to go."]
121:00:31 Cernan: Okay. Let me put my foot on it.
121:00:34 Schmitt: Okay, ready?
121:00:35 Cernan: Yup. (Pause) It's got to loosen up sooner or later. (Pause; Jack uses his full weight again to push the handle to the ground) Okay. That's another good one. When you're tired, I'll do that and you can do this. See, this way, you can get a bigger throw. Okay. Let me know when and I'll do that.
121:00:53 Schmitt: Oh, that's all right.
121:00:59 Cernan: Does it feel like it's loosening up at all?
[On this stroke, Jack pushes so hard on the handle that his toes come up about a foot off the ground.]
[Schmitt - "I was putting every bit of weight and momentum into it that I could."]
121:01:02 Schmitt: Not yet. (Laughs) Excuse me.
121:01:05 Cernan: No, go ahead. (Laughter)
[Jack loses his balance and spins to the ground; he kicks the rack again on the way down.]
121:01:11 Cernan: (Both laughing) Okay, okay, okay.
[Cernan - "This part - where Jack spins around and falls ass-over teakettle - was the funniest thing in the world."]
121:01:14 Cernan: Stay there. Stay there.
[Jack is on his hands and knees. Gene grabs hold of the back of his PLSS and tells him to rock back onto his feet.]
121:01:17 Cernan: Okay, back.
[Jack rocks back on his knees and pushes up with his legs onto his feet, with Gene helping him balance.]
121:01:20 Schmitt: Thank you. (Pause) Oh, my UHT (is on the ground); among other things. Okay. Let's try that again.
Apollo 17, second EVA, Geology Station 3 at Ballet Crater:
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144:50:46 Parker: Okay. We're ready now for your pan and don't forget your scoop.
144:50:52 Schmitt: I won't...Aaaahh! (Pause)
[Jack has knocked the SCB over, scattering full sample bags. He drops to his hands and knees, facing upslope, gets the SCB standing upright, retrieves the sample bags, and stows them in the SCB without getting up.]
144:51:05 Schmitt: You don't mind a little dirt here and there, do you, gang? (Pause)
144:51:16 Parker: No. (Long Pause)
[Jack leans back to get his PLSS over his heels and kicks upright. He makes it, but drops the SCB in the process. He goes to one knee to retrieve it but stumbles and falls on his chest. He gets up successfully and goes to the scoop.]
144:51:53 Parker: Hey, Gene, would you go over and help Twinkletoes, please?
Apollo 17, third EVA, Geology Station 6:
(MPEG video) (Youtube Mirror)
165:36:41 Cernan: Jack, if you got enough film, I'll just come and help you.
165:36:43 Schmitt: Okay. (Pause)
[Gene trips and falls to his hands and knees, apparently without hitting the camera on the ground. He came over a small mound - possibly a crater rim - and, as he came off the mound, caught his trailing left foot, started to tilt sideways over his right foot and lost his balance.]
[Cernan - "I had some speed coming down, even though I was coming cross slope. It was so hard to get up there and so easy to come down, so I was moving. I was coming cross slope because, to come straight down, I probably would have gone head over heels. You couldn't come straight down that hill very fast. It's like skiing. If you go straight down, you're really going to motor. So you've got to shallow up the slope. But I got off balance, got on one leg, and fell into the hill. When I was watching this just now, I thought I was going to roll; but I didn't. I kept my balance pretty well. And I've got to tell you, agility goes along with the responsibility of command; and, to prove the point, I can only refer you to the help I received in getting that deep core out of the ground back on EVA-1."]
[Gene is, of course, reminding us of Jack's spectacular fall at 121:01:05.]
165:36:54 Schmitt: (Having seen the fall) (Are you) okay?
165:36:55 Cernan: Yup. (Pause) (Calling to Bob) Remind me to dust my camera, too, will you?
165:37:02 Schmitt: Don't forget to dust your camera.
[Schmitt - "(Laughing) That's a bad habit of mine. When people ask me to remind them to do something, I'll say it right then so I'm not held responsible for remembering."]
[Gene shifts position so that his feet are downhill. He then pushes back with his hands to get up on his knees and, as his PLSS rotates past the point of his knees, he rises to his feet.]
165:37:04 Parker: Okay. We'll keep track of that for you, Gene.