The team Dillon played in this episode is the Round Rock McNeil Mustangs from Austin, TX in real life. McNeil is in the Round Rock Independent School District (Round Rock, TX) but is actually in north Austin. McNeil and Pflugerville are both in district 14-5A and play each other every year. Because McNeil and Pflugerville are in district - the only way for them to actually meet in the playoffs is in the Region Championship (4 games in) assuming both teams go into the same division in the playoffs.
Dillon played their first playoff game at home. In the top level of Texas HS football, it is very rare for a team to have a playoff game in it's home stadium.