Growth Culture annoyance
While overall I think this is one of the best SciFi movies ever produced, the overly melodramatic portrayal of Dr. Leavitt and the growth culture analysis really bugs the hell out of me. The computer KNEW that one sample produced no growth. After all, the computer displayed the blinking red "NO GROWTH" warning that triggered the mild epileptic response Levitt suffered. At the subsequent midnight meeting they didn't need Leavitt's verbal report since they could have queried the computer directly.
And of course, later during the crisis in Dutton's lab Dr. Hall was able to pull up on the computer the acid/alkaline growth curve.