When Fred gets up from the table at the club to go dance with Diana, his chair disappears and reappears between Lucy and Ethel.
Ricky says that it's 11:30 p.m. and complains that he's tired and "it's past my bedtime" while at the dance. However, Ricky still works at the nightclub and, in previous episodes, is shown getting home well past 2 a.m. so he should be used to being up this late.