In the passport office, the clerk (Charles Lane) makes a point of the fact that his office closes promptly at 5:00. "When the 5:00 whistle blows . . . so do I", he tells Ethel. As 5:00 draws closer, it looks like Lucy isn't going to make the deadline, as she's sleepy from too many seasick pills. The final joke is Fred's: when everyone leaves, with the clock showing 2 minutes to 5:00, Fred plugs in the clock that he has unplugged to make sure Lucy has enough time, and tells the clerk "You can go now." The problem is that less than a minute before everyone leaves, we see Fred sitting under the clock, showing 2 minutes to 5:00, and the clock is plugged in.
When Fred is talking to Lucy in German, he calls her "Fräulein"; which is the German word for "miss". He should have called her "Frau", the German word for "missus".