Revealing mistakes: When Spritle and Chim Chim are "outside" tanning themselves, the stage ceiling can be seen in Spritle's reflector.
Errors made by characters (possibly deliberate errors by the filmmakers): When first visiting the Racer family, Royalton says one line in German - "Pfannkuchen sind Liebchen" - and translates it to "pancakes are love." "Liebchen" is a very old fashioned German word for lover, the correct German sentence would have been "Pfannkuchen sind Liebe."
Continuity: When Royalton visits for the first time, the third button on Mom's shirt is undone. The next time she is visible, the second button is unbuttoned. From then on, all the buttons are buttoned.
Continuity: At the start of the Casa Cristo Race, the moon is a thin crescent. Later that day at the end of the first stage, the moon is full.
Continuity: The first time you see Speed Racer in a race (the opening 5 minutes) the visor on his helmet disappears and reappears.
Errors made by characters (possibly deliberate errors by the filmmakers): Near the end of the film (2:06:51), "The Racing Chronicle" has a typo. "No.42/54 Independent Daily Racing News piublished by THE RACING CHRONICLE,..." should read "published" instead of "piublished."
Revealing mistakes: During the second leg of the Casa Cristo 500, when Speed spins around to avoid Snake's oil spill, the back side of the Mach 5 goes off the side of the road. The effects and angle of the car are the same as if the car was completely on solid ground.
Factual errors: The lines on opening sequence: 'Grace buys a bag of 240 jelly beans. There are 35 yellow ones, 52 red ones, 63 green ones, 26 white ones 41 blue ones and 40 black ones'. They add up to 257.
Continuity: When Togokahn is standing on the stage after the Casa Cristo race you see a lipstick mark on his face but in the next shot it's gone and his face is completely clean.
Revealing mistakes: When the military headhunters at Casa Cristo are given a briefcase of money, all the money has the same serial numbers.
Continuity: Speed's eyes change from a dominate color (brown) to a recessive color (blue-green), which is impossible.