'Oliver Queen' says he'd been "...thinking about developing a boxing glove arrow...." This is a reference to the cartoon-ish arrows (including boxing gloves) that frequented many of the earlier iterations of the Green Arrow character.
Though this episode marks the first time that Gotham City is mentioned on screen - by Geoffrey, just before he gets into his limousine, it was first mentioned in the Smallville Issue 7 story Chronicle.
This is the first time that Chloe and Oliver actually meet.
The original script had Duncan jumping off the roof in an attempt at suicide. Even though Duncan would actually live from this, the producers found this too disturbing and just had him be accidentally hit by a car.
Excelsior Academy is one of the top boarding schools in the United States of America. It was founded in 1877 and its Latin motto is "Memoria Pii Aeterna" (Memory, Pious, Eternal or "The memory of the pious is eternal").