During the montage showing Honey & Pete's first record becoming a hit, the record is shown playing. On screen we see a 78 on the Musicraft label, but in 1957 the record would have been released as a 45 and Musicraft had been out of business for 10 years.
It is obvious that Buddy Knox and his group are lip-synching to their record "Hula Love" since their electric guitars are not plugged in. This is also true of every other act in the movie that uses electric instruments.