Revealing mistake: Near the end, when the captain is walking out of the labyrinth holding the baby, you can tell it's a dummy. The baby does not move in the slightest, you can't even see it breathe.
Continuity mistake: As Mercedes flees after cutting the captain, her hair is done up in a braid, but in the next shot her hair is down and flowing. (01:34:05)
Continuity mistake: When Mercedes flees through the forest to escape the soldiers, the blood pattern, thickness and color of blood on her face changes between shots. (01:33:00 - 01:35:30)
Audio problem: After the final skirmish between the partisans and Franco's Army, a riderless horse trots across the scene from right to left. The foley track uses the sound of a galloping horse (1,2,3 1,2,3) instead of a trotting horse (1,2,3,4 1,2,3,4).
Revealing mistake: The wound to the captain's mouth disappears when he walks out of the labyrinth holding the baby, towards the end of the film. As he is talking to the soldiers the dressing on his face moves showing no cut underneath.
Continuity mistake: When the Captain is stitching his facial wound, the camera pans down to Ofelia hiding by his table, revealing that there is no blood on the Captain's clothing. Seconds later, the Captain approaches the table wearing bloodstained clothing (from the earlier scene with Mercedes). (01:38:20 - 01:39:05)