K.I.T.T. has napalm all over its exterior and drives in the vacuum tunnel to "suffocate" the fire. Immediately thereafter, it leaves the tunnel again. Its exterior would still be so hot that it would be in flames again immediately, making an evacuation of Mike and Sarah impossible.
After the "package" gets his thumb amputated, there's no blood on his hand or in the container the thumb is in.
K.I.T.T. is a highly developed artificial intelligence, yet seems unable to predict that it is stupid to tell a human being that his chances of survival are 1:997,000, which is for a human the same as 1:1,000,000. (Not to mention the fact that they survive in the end, which makes the statement even more ridiculous.) Later on, it says that there is only oxygen for 3.2 minutes, which is again stupid - humans don't count time in tenths of minutes, but in seconds.