TedStixon

Revealing mistake: When Logan slices his abdomen open to pull out the parasite around his heart, watch the (digital) wound at the bottom of the screen right before he says the line "You're not gonna wanna watch this part!" Not only does a small line of blood on the left of the wound simply "blink" into existence instantly at the bottom of the screen right after he pulls the claw out (slip up in rendering), but the wound itself doesn't quite 100% match up with Logan's movements - when he breathes in, the wound doesn't really move properly with his abdomen as it inflates.

TedStixon

Revealing mistake: When Walter Donovan is dying after drinking from the wrong cup, watch the over-the-shoulder shot where we see his hair grow long suddenly - for some reason, this shot was filmed in reverse, as the fire coming from the candles/torches behind Elsa is not burning upwards, but appears to be "sucking" back downwards.

TedStixon

Revealing mistake: Throughout the final fight-scene, anytime Wesley Snipes' face is not on camera, you can often tell that Blade is played by a stunt-double. The double is a bit thinner than Snipes, which gives it away.

TedStixon

Revealing mistake: About 27 or 28 minutes into the film, right before the giant creature flies out at Roger through the doorway, you can see the wall (part of a film set) "wobble" for about a half second as Roger opens the door.

TedStixon

Revealing mistake: When the Ferret's goons are dragging Chev behind the speed-boat near the end, when the one henchman (with all the tattoos) urinates on Chelios, you can see he is holding a small device/hose that is spraying the fake urine out.

TedStixon

Hundred Dollar Baby - S2-E5

Revealing mistake: During the training montage, right as Mac is about to smash the bottle over Charlie's head, you can see Charlie stop what he's doing about a half-second before being hit, and brace himself for the impact, despite not being able to see it coming. This is confirmed on the DVD commentary.

TedStixon

Revealing mistake: When Arthur chops off the Black Knight's first arm, you can see his blade does not slice through the arm, but rather just bumps into the arm, which proceeds to fall off, revealing a fake prop-arm was used.

TedStixon

The Gang Gets Held Hostage - S3-E4

Revealing mistake: When Liam is stabbed in the arm, as he turns around to walk away, you can see the outline of his real arm wrapped behind his back, under his robe for about one full second, revealing that the arm he was stabbed in was a fake prop-arm.

TedStixon

Revealing mistake: When Mad Dog sees the Dragon Emperor walking through the snow shortly after Rick and Evie leave, we see him rub some fog off of the window he is looking through, and it is very clear that the fog is computer generated. It doesn't disappear "correctly" as he wipes it away.

TedStixon

Revealing mistake: Just before the final battle, as the O'Connells are preparing, you see Rick and Evie emerge from behind a rock with guns in hand and cautiously watch over what is happening. In this shot, Evie is holding two pistols, and you can see that one of the pistols (should be on the viewer's right) has a bent barrel, revealing it to be a prop of some sort.

TedStixon