Revealing mistake: When examining the burnt human in sick bay, the body moves his eyelids towards the end of the camera zoom in during the reveal that the human had a Vulcan ancestor. (00:14:30)
Revealing mistake: While Archer and the crew discuss the capabilities of The Xindi vortex technology and whether or not to go to Azati Prime, Archer asks Trip to see the data that Trip has collected from the Degra's ship. The camera pans to the display screen, on which a Mac mouse pointer is visible. It is positioned on the line going downward from the red giant.
Answer: Warp factor has always been inconsistent and hard to pinpoint, or there's too many episodes that contradict the conversion rates. Changes were made in converting warp factor into actual speed between TOS and TNG. It seems ENT reverted back to using TOS method, which is "warp factor cubed" equals how many times the speed of light they traveled. So warp 4.5 means 91.125 times the speed of light (c). Although in "Broken Bow", with the travels from Earth to Neptune and back in about six minutes means warp 4.5 is about 86*c. However, in "The Expanse" episode, warp 5 was 200*c (instead of 125). 1 ly at 91.125*c is about 4 days, but 100 ly would be 400 days.
Bishop73