Holden's trip back to the park to check on the ducks definitely seems to me as an escape from the adult world. The duck pond is quiet, safe, and free from interference from other people, especially adults. Holden feels comfortable in the company of the ducks because they do not pressure him into being something that he feels incapable of.
I completely agree that Holden exists on this line of division between childhood and adulthood and that he seeks, above all, a return to innocence. But there seems to be an ironic compulsion in Holden to escape into adulthood as a means of achieving the metamorphosis or catharsis he so desperately needs.
Hiring a prostitute, renting a hotel room, and accompanying his sister on a trip to the park - these are all moments where Holden poses as an adult and also the moments where his sadness is brought to the surface.
You might want to talk about the fantasy world in which he spends so much time. An example would be when he imagines that he has been shot by Maurice in the hotel and in a film-like scene he goes and tracks him down before blasting him to bits. He certainly does not want to grow up and doesn't want to leave his imagination behind.
I really like the examples you gave....very thought-provoking. Very interesting that others accused F Scott Fitzgerald of the screenwriting 'come-down' too. I do think teens go through a stage though of blaming everyone inc family left,right and centre for everything from lost homework to getting up late - maybe Holden just never grew out of that stage!
I would add that Holden avoids the adult world by blaming others for his issues and trying to show others in a bad light. Such as accusing his brother of selling out to Hollywood when he chooses to be a screenwriter instead of some poor starving novelist. He isn’t a failure at the things he does; he’s a failure because the world is full of "phonies." He blames his relationship troubles on those around him such as accusing Jane of flirting with others. Even his connection to the title is childhood oriented. "If a body catch a body comin’ through the rye . . ." is a childhood nursery rhyme, and one can’t miss the fact that if this were what he chose to do he would still be involved with children.
Look at how he treats the adults in his life. He is rude to the old, sick teacher who wants to counsel him before he leaves school. He seeks refuge at the home of another teacher, and Holden leaves us with the impression that this man has attempted to make a pass at him. Is it true or another of Holden’s attempts to avoid dealing with reality?
A couple of ways in which Holden and childhood are related. Holden's distrust and inability to accept the realities of the adult world are similar to the ways of a child, who refuses to understand the differences between both realms. The notion of the title as Holden as acting as a "catcher in the rye" is similar to the parallels of how adults perceive children, and moreover, reflects a desire of how children wish to live in their own world. The idea of "phoniness" is also a child- like quality, where children see adults in a different lights than adults see one another.
He escapes the adult world by watching Phoebe ride around the merry-go-round. He escapes the adult world by going to the museum and enjoying the stability of nothing changing. He escapes adulthood by fantasizing of saving kids falling off a rye field cliff and being the catcher in the rye.