Revealing mistake: When Eddie sits on the bench and the hippo sits down, you can see Eddie bounce off the bench before the bench even moves. (00:09:10)
Revealing mistake: The streetcar railway tracks are simply metal strips laid in the road. When Eddie jumps off the back of the streetcar's bumper, you can see that the rails are not in full contact with the road, as there are visible gaps between the rails and the road surface. What's more, the rails do not have the grooves that would be necessary for the cars' wheel flanges. (00:10:10)
Revealing mistake: As soon as Eddie walks into the Ink & Paint Club to see Donald and Daffy on stage, a shadow of one penguin's drink tray is cast on the wall near stage left. However, the penguin's shadow isn't animated into this shot. Instead what we can see is a shadow of the pole, which was used by puppeteers to carry the tray around the club before any animation took place. (00:15:00)
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: After Bongo the Gorilla Bouncer tosses Eddie into a pile of garbage cans in the back alley, Eddie lifts himself up and here we can see that he's wearing knee pads beneath his pants. (00:21:25)
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: 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)
Revealing mistake: When Roger takes a shot of bourbon and blows his top, it causes most of the glass objects in R.K. Maroon's office to bust into pieces. In some instances you can see an explosive charge breaking the glass - like the giant angel statue at the center of R.K.'s trophy collection. (00:24:00)
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: When Roger is bouncing on Eddie's bed, the landings are not in time with Roger's feet. (00:38:45)
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: 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: In the shot where Roger looks out of Eddie's apartment window to see the weasels approaching, you can see how their animations overlap the window sill as they cross the street. (00:40:20)
Revealing mistake: After shooting their way into Eddie's apartment, the weasels start walking in and cast long shadows on the floor. But the only shadow visible in a reflection on the nearby glass doors is that of Wheezy's Tommy gun. (00:41:10)
Revealing mistake: A string is visible suspending Greasy's gun when Smart Guy orders everybody to search Eddie's apartment for Roger. (00:41:55)
Revealing mistake: After getting a mouthful of soap from Eddie, Smart Guy is thrown across the room and loses his gun. When the gun hits the wall you can see it dangling from a puppeteer's string in mid-air. (00:42:15)
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 a bar of soap knocks Wheezy into the window blinds, he casts no shadow on the wall, but his Tommy gun does. (00:42:30)
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)
Answer: Valiant also shares his name with Arthurian comic strip hero Prince Valiant, who wields a singing sword, Flamberge.