Continuity mistake: There is a rather tall plant beside the Walsh's front door, in the corner, that keeps moving from the corner to the front of the draperies, then back again, throughout the early scenes. (00:06:50)
Continuity mistake: After removing the 'copper bone' necklace from Chester Copperpot, when Mikey puts the necklace around his neck, the cord's knot moves farther up between shots.
Continuity mistake: When Jake Fratelli searches through Chester Copperpot's wallet, it faces the opposite direction between shots - note the driver's license. (01:08:30)
Continuity mistake: Just as Data hands Mouth the lantern and Mikey tells him to translate, Mikey stands between Data and Mouth, but next shot as Mouth says, "Copper bones. Westward foams. Triple stones," Mouth is between the other two boys. (01:09:40)
Continuity mistake: When Data crashes through the screen door, sending Chunk to the floor with the statue, in the first shot there is a long bright stream of sunlight shining on the carpet, between Chunk and the stereo which disappears in the next shot. (00:08:55)
Continuity mistake: When Mikey pulls the cord to release the bowling ball, the rocking chair is parallel to the railing, facing the porch, but in the opening shot of the house it was closer to the stairs and facing the yard. (00:05:10 - 00:07:35)
Continuity mistake: When Mouth stands by the door cracking up at Chunk's 'Truffle Shuffle' and in more following shots, there is nothing on the wall behind him between the hutch and doorway. After Data breaks through the screen door there is a large painting hanging there. (00:07:30)
Continuity mistake: When Brand runs down the stairs to take the paperwork from Mr. Perkins, the large hanging plant that should be over Mikey is gone, but it was there when Chunk arrived and is back later. (00:07:25 - 00:20:25)
Continuity mistake: When Chunk is picked up on the road by the Fratelli brothers and thrown into the back with the corpse, he starts screaming. His red jacket hangs off his shoulder, but rights itself between shots. (00:49:40)
Continuity mistake: On Inferno's deck, when Data stubbornly takes a stand against the Fratellis, Mikey's and the others' facial expressions and positions repeatedly change between close-ups and wideshots.
Continuity mistake: When Troy sends the bucket down the well, in shots facing Andy and the rest, she stands behind the bucket, but in the shots facing Mikey as he tries to convince them all to continue on, Andy's left foot is atop the bucket, and so on.
Continuity mistake: After Mikey sets off the falling boulders by pulling the wire, when Brand climbs up to move the rock Stef and Andy are standing about four feet apart, but in close-ups they are shoulder to shoulder, and so it goes over and over again. (00:57:20)
Continuity mistake: After they find the skeleton key, when Mikey lifts the string in the dirt, which triggers the scythe to cut the rope, the rope differs between shots. (00:56:20)
Continuity mistake: When Stef finds the newspaper with the mugshots over the telephone and shows it to the others, how the newspaper is folded differs between close-up and wideshot. (00:42:50)
Continuity mistake: When Chunk is in the freezer collecting a bunch of the ice cream in his arms, their positions change between the wideshot and close-up, when he sees the frozen corpse. (00:43:35)
Continuity mistake: When the Inferno sails past everyone on the beach, in the close-up of Mikey blowing a kiss and saying thanks, he has a blanket wrapped around him, but next wideshot the blanket is on the rocks, at his legs. (01:48:10)
Continuity mistake: When Chunk runs to the window, to watch the police chase, in the interior shots he stands in front of divided window panes, but in the exterior shot facing him he stands in front of a single pane of glass. (00:04:10)
Continuity mistake: In the attic, after Mikey finishes his story about One-Eyed Willy, in a close-up Chunk stands up and walks toward the frame which lies sideways between the crate and another frame. When it cuts to another close-up, his foot knocks over the now front facing framed Chester Copperpot news article. Next shot, when Chunk lifts it, the frame and taped back differ and the loose wire is now attached properly. (00:18:45)
Continuity mistake: On Inferno's deck, when Sloth jumps rope with Francis and Jake, in the close-up of his feet he wears all black high-tops with black laces, but in the previous and following shots he wears black high-tops with white soles and laces.
Continuity mistake: When Data shoots the blue suction dart at Mama Fratelli's gun, she drops the gun and when it falls below deck Jake's Sporto boot is seen on Mama's right (viewer's left), but in the previous and following shots Jake is standing to her left, beside Francis. (01:31:55)
Answer: According to Mikey and Mr. Walsh, one of his crewmen must have taken the map and fled when One Eyed Willie was murdering his crew. This is substantiated in the novelization.