Deliberate mistake: When Eric Kriegler shoots in the biathlon, the camera looks from behind the target, through the holes of the targets he has already hit. But in the next clip it can be seen that little flaps fall down and cover the holes when they are hit.
Deliberate mistake: In the last sprint towards the finish line, before they have to race on foot, the Lamborghini passes Fenderbaum and Blake. The red Ferrari they are supposed to be driving, is on the bed of a truck being towed. Notice the height difference between the two cars; about ten seconds later the two cars are pretty similar in height. (01:23:05)
Deliberate mistake: O'Niel needs a sample of a dead man's blood to test for toxic drugs. So he visits the corpse, which has been dead for quite some time and is lying on its back, and proceeds to insert a hypodermic syringe into the dead man's frontal neck, extracting the sample. But blood pools low in the body soon after death. There ought to have been no blood available from that location of the body. To get blood, O'Niel should've punctured the corpse's underside.
Deliberate mistake: After Perseus and his men defeat the scorpions, Kalibos goes after him, lashing his whip. But curiously, the whipping leaves no visible marks.
Deliberate mistake: When Max opens the dog food, the lid should be all jagged because of the type of can opener he uses, but when dog and the gyro captain have the can the lid is cut smoothly. This was done so dog didn't get cut whilst eating out of the can.
Deliberate mistake: When the lion appears during the beach scene, the timing doesn't add up. In the first takes it makes its way halfway out to the sand, while Jane is bathing in the ocean. After Jane is done and redresses herself, the lion suddenly emerges from the place it first appeared.