Apollo 11 landed 3 miles downrange and was almost out of fuel due to not fully depressurizing the space between LEM and CM. That little "pop" when they undocked added enough delta-v to send them way downrange. Not to mention the 1201 and 1202 program alarms due to an overwhelmed computer trying to deal with data coming from both landing and rendezvous radar.

Apollo 12 was hit by lightning twice on liftoff. Knocked just about everything electric in the CM offline. Could have been really bad for a number of reasons. That's the "SCE to AUX" call that made John Aaron a 'steely-eyed missile man'.

Apollo 13 - That story is well-known. Also the best space movie ever made.

Apollo 14 - There was a small ball of solder floating around in the abort switch in the LEM. Fortunately they saw the intermittent signal coming from the switch and were able to put a very clever workaround in place to ignore that signal during descent. Without that workaround, if the solder ball had touched the contacts at any point during descent, it would have triggered an abort, cut the descent stage loose and flown right back to the CM.