Revealing mistake: When the weasels are at Eddie's apartment and Roger is handcuffed to Eddie, Roger runs under the bed and drags Eddie on the floor. As he pulls him you can clearly see a board with wheels under Eddie that is pulling him under the bed. (00:38:50)
Revealing mistake: Watch when Baby Herman confronts Eddie Valiant in the hallway at Valiant's office. The screen image may be of Herman, but the studio lights clearly cast the shadow of the puppet-machinery used to animate Herman's actual prop cigar in the baby carriage. (00:34:45)
Revealing mistake: Close to the film's climax, when Doom is showing off his Dip Machine, we see one of the weasels hoisting a canister of Dip up a ladder. If you look close, you can see a large wire pulling the canister up. This was seen in the VHS version and may have been corrected in the DVD, I am unsure. (01:19:20)
Revealing mistake: When Roger is bouncing on Eddie's bed, the landings are not in time with Roger's feet. (00:38:45)
Revealing mistake: When Judge Doom has transformed into his toon-self for the first time, he bounces after Eddie with yellow springs on his feet. Between when he takes off and when he lands, they show 4 different shots. In shots 2 and 3, you can see about 6 black suspension wires running into his clothes and carrying him through the air. (01:26:30)
Revealing mistake: When Valiant came upon the ugly Jessica look-alike, and she began to chase him, the chase ends with Eddie moving the roadline towards a wall, the results of which are her crashing into it. When Eddie throws the line to the wall, you can see that the cartoon line goes a bit "into the filmed wall" and covers a part of it. (01:13:30)
Revealing mistake: Before Benny crashes into the pole while carrying Eddie and Jessica, they show a shot in front of it of him coming towards it, and you can see the pre-cut line in the pole where it breaks in half. This is better seen on the VHS version, it is harder to see on the DVD, but it's there. (01:16:10)
Revealing mistake: When the weasels are in Valiant's apartment and the leader says, "Step outta line and we'll hang you and your laundry out to dry," you can see the shadow of the mechanical arm used to hold the gun cast on Hoskins. (00:42:50)
Revealing mistake: When Wheezy and Psycho laugh at Smart Guy after he has fallen down the stairs, if you look closely you can see the wires holding Wheezy's machine gun up. (00:42:20)
Revealing mistake: When Judge Doom knocks Eddie off the Dip machine, note the Acme Curve Ball boxes in the background that appear to be written backwards, revealing a flipped shot. (01:26:30)
Revealing mistake: When Daffy gets thrown into Donald's grand piano, a wire is visible on the upper left side of the screen - closing the lid on his beak. (00:15:40)
Revealing mistake: During the piano duel finale, Donald blasts a cannon at Daffy and the grand piano collapses - seemingly from the impact. But if you look closely there are actually ropes pulling the piano's legs from somewhere offstage. (00:17:05)
Revealing mistake: When Eddie and Roger are using Benny the Cab to run from the weasels, Eddie reverses gears and backs into the alley. It may be Benny the Cab's image onscreen, but a shadow on the ground actually reveals the go-cart which Eddie uses for the take. (00:58:40)
Revealing mistake: After Lena Hyena plants a kiss on Eddie, he tumbles down the street and lands face-first onto a solid white line. Pavement is animated into this shot, however a reflection of the stage floor is still visible. (01:13:20)
Revealing mistake: As Roger gets ready to take a drink of bourbon in R.K. Maroon's office you can see a moving shadow on the desktop - which is that of a mechanical arm used to hold the shot glass. (00:23:40)
Revealing mistake: After Eddie tells Roger that his handcuff keys are missing, they leap over the bed as the Toon Patrol sirens approach. When Eddie lands on the floor, his bedsheets get disturbed by a large blast of air - most likely the backfire of a safety cushion that was hidden behind the desk to break his fall. (00:40:10)
Revealing mistake: At one point where Roger drags Eddie over to the electrical outlet spy hole in Dolores' secret room, Roger says "This will be a great place to hide." Both of them are handcuffed together in this shot, but Roger's shadow is not animated into his cuff. (00:44:20)
Revealing mistake: After being flattened by the steamroller, Judge Doom staggers over to the compressed air tank and reinflates himself. When his black hat pops off, strings can be seen pulling it up. (01:29:45)
Revealing mistake: When Benny the Cab jumps onto a bridge with Roger and Eddie, a red Ford De Luxe skids to avoid a collision. Notice how tire tracks from a previous take are visible on the pavement. (00:59:35)
Revealing mistake: Hoskins and Maroon break the news to Roger Rabbit, and Maroon gives Roger a drink. When he pours the drink you can see a clear plug in the neck of the bottle, and right before Roger Rabbit drinks you can see there is nothing in the glass. (00:23:40)
Answer: Valiant also shares his name with Arthurian comic strip hero Prince Valiant, who wields a singing sword, Flamberge.