The scene where Pi's father explains how every single animal in the zoo can kill them. Probably doubles as terrifying for those with animal phobias.
The scene is capped off with Mr. Patel telling his son that guinea pigs are not dangerous...only for Pi to point how that they are dangerous when not domesticated.
Pi and the Japanese insurance agents discussion getting derailed into an argument over whether bananas float. Finally Pi hands them a banana, points to a sink and tell them to try it out for themselves. They are amazed when the banana floats.
Most of Pi's interior monologues. Particularly the one where he talks about what he thinks is a ridiculous part of Christianity by comparing it to a situation where his father feeds him to the lions because the lions are on an eating spree.
Pi: Yes Father. That seems the right and logical thing to do.
Father: Hallelujah my son!
Pi: Hallelujah father!
Pi tries to show Richard Parker who's boss by marking his territory. Richard Parker responds by spraying him back.
Pi: Step 4: disregard steps 1-3.
Pi's response after his father says they'll be sailing like Columbus.
Pi: But Columbus was looking for India!
Pi crosses himself and says "Amen" after praying before dinner and the following conversation ensues:
The Writer: I didn't think Hindus said "Amen."
Pi: Hindu Catholics do.
The Writer: You're a Hindu Catholic?
Pi: We get to feel guilty before hundreds of gods.
Pi's brother mocking his multiple religions: "So, Swami Jesus, will you be making the hajj this year?"