Other mistake: In the chase scene on I19 Hauser pushes the throttle forward to accelerate but in the police cruiser the throttle is pulled backwards to accelerate.
Factual error: If you drive a straight shaft through the earth's core from London (52deg N, 0deg E) down to the other side of the world it would come out at 52deg South, and 180 East. Which is somewhere out in the South Pacific ocean over 500km from New Zealand's South Island, not on mainland Australia.
Continuity mistake: When Quaid is fighting Cohaagen he is wearing a timer on his right wrist. Near the end of the fight it disappears and then re-appears.
Continuity mistake: After Hauser shoots Harry in the head, there is no bullet wound in Harry's head when he falls on the floor.
Answer: The absence of the tattoo on Quaid's arm hints that the whole scenario could have been a memory, brought on by Rekall.
THGhost