A Comcast Corp. official told a judge he made a mistake in reviewing a contract a decade ago that may now result in the premature shutdown of the company’s emergency-call services, endangering hospital patients, first responders and 911 callers.

Comcast sued to block contractor CX360, which is owned by Apollo Global Management Inc., from halting the automated phone-menu service months before its contract expires. CX360 threatened the shutdown after Comcast decided to replace it with another operator.