Dawson Casting: Subverted and played straight. In the beginning of the series the main characters were supposed to be around 24. They were played by 22 year old Ryan Reynolds, 26 year old Richard Ruccolo and 32 year old Traylor Howard, but they made it believable. In the second season however Reynolds was paired off with the 31 year old Suzanne Cryer and it did show.
Lampshaded in the second episode of the third season, with an entire subplot devoted to Berg realising he's too old to keep working at the pizza place after the new employee refers to him as "Sir".
Friday Night Death Slot: After ABC moved it to Friday, they tried moving it back to midweek as a two-week test to see if anyone would watch. It failed and the show was canceled.
Keep Circulating the Tapes: Finally averted, with the first season being released on DVD in April 2012, and the remaining three seasons scheduled to follow later in the year. Over a decade after the show went off the air, and long after Ryan Reynolds & Nathan Fillion have achieved greater popularity with other roles.