The myth that Harrison Ford and Ridley Scott "hated each other"
Ford was far more passionate for this project than people wanted to believe.
He was constantly giving the less experienced actors advice, he was highly involved with the script and was far from being a prima donna on set. I think anyone would be pissed off, if they had to keep constantly shooting the same scenes in the rain for weeks on end.
Ridley demanded a lot of takes from all the actors in this, in fact i'd say he was shooting as many takes as Kubrick in his earlier years. One of the actresses (I forget who) had to keep falling into a wall and was covered in bruises. Sean Young was made to smoke tons of cigarettes and developed a cough. So Ridley gave them all a hard time, and they all understood that they were making something great. Ford and Scott were fine, and that's why they're working together again.