When Chucky has Andy take the train to some old abandoned houses he (Chucky) goes into one of the houses. He then turns on the gas stove so he can get back at his former partner in crime to fire his gun. Of course he succeeds and the building blows.
Question is why would an old abandoned house still have gas turned on? That, along with the lights, would have been turned off long ago.
Then too, why does the guy just open fire as soon as he opens the door?
I don't think it's entirely implausible because I know during the winter months they can't shut your heat or water off if you're behind in payments because they worry that you'll freeze to death and that your pipes would burst but the house does look like it's been abandoned for some time so there wouldn't be a need for heat hence a working gas stove. Maybe it was a case of Chucky getting lucky and knowing that his friend is a paranoid moron who would open fire without thinking. I consider it luck all the way around for Chucky I mean, the fact that he has a second chance at life (so to speak) means anything is possible. The bigger question, of course, would be how did Chucky know Eddie would be in that house? Was that also a lucky guess? Chucky seemed to know for certain unless that was a house they both used to do their "dirty deeds" that the cops weren't aware of and they paid the utilities usually which is why there was heat? Beats me.
Or it just could be that we needed to see Eddie die because Chucky vowed to kill him and the detective and it made for a convenient way to kill him off and provide tension and suspense because we see a 6 year old kid near a home that we, the audience, knows is about to explode?
As for Andy riding on a train by himself? It's not that out of the ordinary. I'm from Chicago myself and my father grew up in the 70s and told us he was taking trains and buses alone as early as 8 years old. He had a tough childhood his mother was quite selfish and wasn't a very good mother so she would arrange for doctor or dentist appointments and my dad would go alone and one time when they moved my dad went to the same school and had to take 2 city buses to get back and forth. I know I was riding the bus and taking the train with my friends when I was 10 back in the 90s. I guess it's not that big of a deal if you're from a big city and Andy looked like he knew what he was doing. If he was alone and looked lost I'm sure someone would've approached him and asked him if he was separated from a parent or guardian. And it could be a case of "I don't want to get involved" it was the 80s after all. I'm sure if someone saw a kid in NYC or Chicago on a train alone these days they'd be expecting John Quiñones to pop out of nowhere questioning why they didn't ask the kid why he or she was alone in a What Would You Do? episode.