Revealing mistake: When Eddie is carrying Roger into Dolores' secret room, keep an eye on the swinging light. At some points, Roger's image is translucent and the light can be seen right through his ears. (00:44:10)
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: Tire tracks from a previous take can be seen on the pavement as Benny the Cab skids to avoid a collision with the Red Car. (00:58:30)
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: During the Toon Patrol chase, before the cab enters the alleyway there's a wide shot of the cab making a fast turn. Valiant has his head down, with his hat covering his face and his body totally motionless, opposite to what he looks like in the close-ups where he is grabbing the steering wheel, his head up and controlling the car, thus revealing that the actor was replaced by a dummy in some of the shots. (00:58:40)
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: When Eddie's Plymouth skids out from R.K. Maroon's lot, a large section of the Red Car's railway track gets torn from the pavement with the greatest of ease - revealing that the track is actually just a set of metal strips laid out in the center of the road. (01:07:40)
Revealing mistake: When Toon Town's red curtain rises for Eddie in the long tunnel, the reflection on the pavement doesn't move correspondingly. (01:10:00)
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: 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: Eddie heads into Toontown with an oversized animated gun. As he lurks into an alley, his gun is a plastic prop. During filming, Hoskins would carry the prop gun and the animated gun would be superimposed over it, but the animation wasn't applied to the gun in the alley. (01:13:50)
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: 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: In the Acme warehouse, Roger's shadow disappears a split second before the bricks land on him. (01:21:50)
Revealing mistake: Just before a conveyor belt drops the vase upon Eddie's head, an overhead shot shows him pointing at Smart Guy, but actually Eddie points much further left in relation to where Smart Guy is standing. (01:25:10)
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 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 Eddie is using the magnet to pull Judge Doom toward him, you can see the wires attached to Doom's shoulders used to move him. (01:27:05)
Revealing mistake: When Eddy is fighting Judge Doom, Eddy is holding a giant cartoon magnet. He then attracts Judge Doom's sword and when Eddy drops the magnet it is attracted to a steel drum. If you look at the bottom of the drum you can see two strings on the bottom of the drum as it moves towards Bob Hoskins. (01:27:10)
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)
Answer: Valiant also shares his name with Arthurian comic strip hero Prince Valiant, who wields a singing sword, Flamberge.