I've been aware of the squeaky bass drum pedal from the mid seventies, after I had a serious upgrade of Hi-Fi, so I'm surprised that Page claims it was un-noticed at the time of recording. I would have thought that a master played through studio monitors would have revealed it at the time. Yes, The Ocean and the ringing phone: again, it wasn't until the advent of the CD that people started asking me if I heard the phone on a Led Zeppelin track, and it always raised eyebrows when I instantly answered "yes, during the guitar solo on The Ocean" - that, and overloading microphones (crackling noises).
RB