Whilst Carol is talking to 'Dr. Linus' (actually Jerry Webster) at the aquarium, and talks about trust, and how a woman 'instinctively knows' when a man can be trusted, they're standing in front of a tank mock-up, of what appears to be a large fish, looking to capture prey; what appears to be a small worm. Just when Carol says; 'and, you, doctor, can be trusted,' it turns out the 'little worm' is actually part of a big angler fish, and it's huge jaws open, and pull in IT's prey.
The storyline is somewhat similar to that of Pillow Talk (1959), another Doris Day/Rock Hudson/Tony Randall vehicle - both movies involve Day's character falling in love with Hudson's while he is pretending to be someone else.
The trivia items below may give away important plot points.
The original ending had Carol and Jerry getting drunk on VIP and checking into a hotel. Doris Day insisted the concluding events be rewritten, having Carol and Jerry get married in their drunken state before going to bed.
The proposal the 2 men from the liquor industry make to Jerry - giving him 20% of the $60 million the liquor industry spends on advertising per year ($12 million in 1961) is now worth $97,122,494.43/year.