In an earlier season, Quagmire is revealed to be 60 years old, but for this episode he is affected by the 50-age drinking limit.
Meg appears but doesn't have any lines.
When Peter says, "This is for all the teachers who told me I'd never amount to nothing" this is a reference to the song, Juicy by Notorious B.I.G.
Individual state governments can pass a lot of laws that differ from federal laws. Think legalized recreational pot, legalized same sex marriage. 33 states permit localities to restrict alcohol sales, possession, or consumption, in those states there are many dry counties and cities. Three states are by default dry (alcohol prohibited) but any county can pass local law permitting alcohol. Rhode Island allows local governments to prohibit or restrict alcohol by public referendum.
Underage Peter is Adam West's 100th speaking appearance.