Pikachu defeats Geodude with an electric attack despite it being part ground type and therefore immune to electricity.
In the original Japanese dub, Ash is told that both of Brock's parents left Brock and his siblings to become Pokemon trainers and never returned. 4Kids Entertainment didn't think it would seem right for Brock to have two deadbeat parents, so the line was changed in the English dub stating that only his mother passed away while his father left to become a Pokemon trainer and never returned.
First episode we meet Brock.
Ash's advantage over Brock should not have technically worked; Ground-type Pokémon are immune to Electric-type moves. This is the first of many times Pikachu's Electric attacks defy type match-ups to change the results of the battle. However, there are multiple future instances in the anime where Electric moves have not worked against Ground-type Pokémon, including Onix.
Team Rocket doesn't blast away in this episode. This is also the first episode in which Team Rocket has no effect on the plot as well as introducing their pitfall trap gag.