Alternate Character Interpretation: Some fans have theorised that the final conversation between Tom and Summer in the park didn't actually happen - with the audio commentary suggesting that it could just be all in Tom's head. But the director and screenwriters disagree on this.
Award Snub: No Best Original Screenplay nomination?
Big Lipped Alligator Moment: The spontaneous dance sequence (the morning after Tom and Summer have sex for the first time), which is simultaneously a glorious movie musical dance scene and a hilarious parody of movie musical dance scenes.
Canon Sue: Summer, probably intentionally as we see her entirely through Tom's perspective. It's pointed out a few times that idolising a woman is not healthy at all. If one reads between the lines, Summer is a rather destructive presence in Tom's life - but she at least has the good sense to end the relationship when she realises.
Hollywood Homely: Downplayed. It's said earlier on how Summer is out of Tom's league, and a Jerkass at a bar reacts with shock at them dating. This is ignoring the fact that Tom is played by Joseph Gordon Levitt. He's dressed down in unflattering clothes and a slightly nerdy hairstyle but it still seems odd that Tom is supposed to be considered unattractive.
Jerkass Woobie: Tom's misunderstanding of Summer and their relationship is his fault; but it's never out of maliciousness, and he does genuinely care for her, and it's hard not to feel sorry for the guy. That being said, his Entitled to Have You attitude is shown as very damaging and a little dickish on his part.
Misaimed Fandom: Though he is a sympathetic character, Tom is being very childish in his expectations and is making some big mistakes, even if he's not doing it intentionally. Some people didn't pick up on this Aesop resulting in this trope.