On April 13, 1966, the album's final vocal overdubbing session, for "Here Today", concluded a ten-month-long recording period that had begun with "Sloop John B" in July 1965. The album was mixed three days later in a single nine-hour session. Most of the session was spent mixing down the vocals to fit with the instrumentals, which had already been locked into one mono track. The album's original mono master ultimately featured many technical flaws that contrast the refined arrangements and performances. One of the most prominent examples occurs in "Wouldn't It Be Nice", where an audible tape splice is heard between the chorus and Mike Love's vocal entrance in the bridge. A similar anomaly is heard in the instrumental break of "Here Today", where a distant conversation was accidentally captured during a vocal overdub. In David Leaf's view, "It's not sloppy recording, it's part of the music."