The Princess Bride (1987) - 46 mistakes
Directed by Rob Reiner, starring André the Giant, Billy Crystal, Carol Kane, Cary Elwes, Chris Sarandon, Christopher Guest, Fred Savage, Mandy Patinkin, Mel Smith, Peter Cook, Peter Falk, Robin Wright Penn, Wallace Shawn
Revealing: When Fezzik is about to climb the rope going up the Cliffs of Insanity with Inigo, Vizzini and Buttercup all harnessed to him, Buttercup is the most visibly seen (besides Fezzik) in the camera. When Fezzik starts to ascend the rope, it is clearly obvious that Buttercup is a stuffed dummy because her head is flopped completely back.
Revealing: When Humperdink and the six-fingered man are on horseback near the coast, discussing strategy, you can tell that the ocean is a matte painting, as the waves and whitecaps never move. Submitted by wizard_of_gore
Continuity: Fezzik tries to crush Westley on a boulder. We see him doing the crushing spread-eagled, but when the angle changes to a close-up, he is holding Westley's wrists tightly under his chin. Submitted by Sereenie
Continuity: The iocaine-poisoned wine cups change position on the table between shots. Submitted by EmilyGrace
Visible crew/equipment: In the duelling scene between Westley and Inigo, right after Westley has done his swinging on the bar and they go into the next shot, you can see Inigo jump up on a higher platform of rock, and then immediately after him, you can see Westley BOUNCE off the concealed trampoline onto the platform of rock.
Continuity: This is the scene after Westley gets tortured and he, Indigo and Fezzik are on the stone wall in front of the castle. Fezzik says, 'You moved your head, does that make you happy?' Wesley sort of turns his head and it falls in front of him towards his left. In the next shot, his head is against the wall leaning to his right.