Question: There was supposedly one episode that ended with SpongeBob, Patrick, Squidward, and Mr. Krabs all laughing in a boat. The laughing then silences, eventually to a stop. Then SpongeBob, Patrick, and Mr. Krabs walk out of the boat, and Squidward eventually walks out too. Which episode is this?
Question: How did the streetcar, phone booths, and vending machines end up in the digiworld?
Answer: We are never told as to how they got there.
Answer: People who built the digital world most likely had them sent there. Gennai tells the kids in the last episode that the streetcar was from San Francisco, and he asked them to take it back for him.
Question: Throughout the series, Sarah has been shown to have excessive anger, as well as hostility towards her older brother. Is it ever revealed why she is so angry?
Answer: She's just a spoiled, bratty younger sister.
Answer: I believe this is the Season 6 episode "Spongicus".