Continuity mistake: In the climactic scene where the Red Car is about to "Dip" Roger and Jessica, one shot of Eddie (shot upward from the ground) also includes the hook that Roger and Jessica are hanging from. However, Roger and Jessica are not animated into this shot.
Continuity mistake: The toon patrol car hits the 2 police motorcycles in the middle of the long alleyway, yet after they crash the cops then land in the middle of the street. (00:59:25)
Continuity mistake: In the scene where Valiant gets his check notice he puts it in his left chest pocket, but when he gets in front of the trolley operator to pay he reaches in his left jacket pocket then it quickly shows him holding it showing the trolley operator. (00:08:55 - 00:09:55)
Continuity mistake: When Eddie pours out his whisky, the way he holds the bottle changes between shots. (01:06:35)
Continuity mistake: When Eddie hears his friend has been laid-off, Delores puts her hand over the glass to remind him he needs to have the money by Friday and she takes her hand off the glass when the camera pans up to her face. When it cuts back to Eddie her hand is still over the glass. (00:12:00)
Continuity mistake: When the movie starts and Herman is launched outside the park, the rattle balls on the bars disappear. (00:01:25)
Continuity mistake: When Judge Doom is about to dunk the squeaky shoe into the Dip, it seems to stick itself in for him, even though it looks rather scared. (00:33:35)
Continuity mistake: When Roger goes to the Acme warehouse, he brings the gold-plated gun that was in Eddie's car after Eddie took it from RK Maroon. This is a real (not-animated) gun, and when Roger is talking to Benny before going into the warehouse, he's holding a real (non-animated) gun. After Roger bursts through the drain, the gold gun he's holding is animated. (01:21:25)
Continuity mistake: When we're first introduce to Roger, the table on the left disappears between shots, and the pillow he rests on keeps moving closer to/away from the door randomly. (00:01:00)
Continuity mistake: After unveiling the dip machine, Judge Doom explains its functions while waving his cane in the air. But in the following shot his cane is planted firmly on the floor instead. (01:19:15)
Continuity mistake: When Roger blasts out from beneath the Acme Factory grate, Judge Doom lifts his head twice in successive shots. (01:21:05)
Continuity mistake: As Donald plays both pianos at once, the white piano's lid alternates from being closed to open between shots. (00:16:40)
Continuity mistake: After Eddie kicks out the stool and forces a hard-boiled egg into Angelo's mouth, the eggshell fragments on the bar rearrange themselves into a neat pile. Also, two more eggs appear on the bar, which can be seen after Angelo gets on his feet and turns around. (00:13:40)
Continuity mistake: When Eddie breaks out the magnifying glass to get a better look at Marvin Acme's will, his left thumb jumps to a different position on the photo between frames. (00:36:20)
Continuity mistake: Before Eddie grabs Roger to toss him out of the apartment, a blanket hung over the edge of the pull down bed rearranges itself between shots. (00:37:25)
Continuity mistake: When Eddie starts browsing through his Catalina pictures, a white cup on the desktop changes its location between shots. (00:26:15)
Continuity mistake: After blowing his top in R.K. Maroon's office, Roger rests his head on the desktop. Watch how a black ledger appears beneath Roger's head by the time R.K. and Eddie walk over to comfort him a few moments later. (00:24:10)
Continuity mistake: After Roger interrupts their kiss in the theater, Dolores looks into Eddie's eyes and says he'd better get going. In the next shot, they're suddenly looking away from each other. (01:03:25)
Continuity mistake: After fooling Lena Hyena with a road divider, Eddie's necktie blows over his left shoulder. But once the angle changes, his tie is suddenly hanging down again like normal. (01:13:30)
Continuity mistake: When Eddie and Baby Herman are in the hallway discussing the late Marvin Acme's will, Eddie repositions the baby carriage and starts unlocking his apartment door. He then turns around to face Baby Herman, but between shots his body rotates back to its original position. (00:35:20)
Answer: Valiant also shares his name with Arthurian comic strip hero Prince Valiant, who wields a singing sword, Flamberge.