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.
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.
During the second leg of the Casa Cristo, Snake extracts oil from the back, thus causing Speed's tires to lose friction and almost to lose the race. This should have the same effect on Racer X and Togokhan, but it doesn't, despite the fact that they were directly behind Speed.
At the Grand Prix, everyone in the crowd (including the Racer family) makes the exact same movement - once after the second jump-jack of the car, and the second after the commentator shouts "He's back in it!"
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.
Speed's eyes change from a dominate color (brown) to a recessive color (blue-green), which is impossible.
During the first race, Speed is driving the Mach 6. Although many believe this car wasn't built until just before the final WRL Grand Prix at the end of the movie, the Mach 6 was Speed's main car until it was destroyed at Fuji. The Mach 6 was rebuilt for the Grand Prix since the Mach 5 still had the defensive features from Casa Cristo which weren't allowed.
When Spritle and Chim Chim are "outside" tanning themselves, the stage ceiling can be seen in Spritle's reflector.
When the military headhunters at Casa Cristo are given a briefcase of money, all the money has the same serial numbers.
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.
Any time a large of number of spectators are shown in the audience of a race, close inspection shows that they are the same extras shown over and over.
Little Speed's school test reads: '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.
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."
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."