This is an interesting episode. Though Bud seems convinced Flipper can talk, Bud is only half-way convinced and is easily convinced that he really can't talk. Yet Bud is imaginable enough - and young enough - that he really DOES believe the professor at face value.
Porter Ricks is quickly frustrated by Bud's imaginations and tells his children to get to their homework. Though he knows Flipper really can't talk, he still takes time out to let Bud try to prove the opposite to him. But and Flipper's relationship seems to suffer when Flipper refuses to talk to Bud when it really counts.
Of course, we see the protective daddy bear at the end when he rescues Bud and Flipper from the bad guys. We always see plenty of father-son and Bud-Flipper interaction. Though the story is a bit hard to take in, it's still a good development story of the Bud/Flipper special relationship.
One thing that gets me and is a little hard to comprehend is that the professor just happens to find Flipper's caller right near the beach and he knows it's what the boys use to call Flipper. Bud just "happened" to drop it when he got mad at Flipper. And the professor knew exactly what it was...
Another thing that got to me was the professor's sudden change of heart. It was too abrupt...