Okay, I've seen Big Trouble like a million times... Am I missing something with Egg Shen's bus tour?

Alright, fellow Big Trouble fanatics! Hannahfilmbuff here, back at it again watching this glorious mess for, like, the 50th time. I swear, every time I watch it I catch a new detail. But there's one thing that still bugs me after all these years. It's about Egg Shen's bus tour. So, Egg Shen conveniently shows up right when Jack and Wang are looking for a way into Lo Pan's underground lair, right? And he just HAPPENS to run a tour bus that goes... basically right there? Okay, I know it's a movie and we're supposed to suspend disbelief, but does anyone else find that a little too convenient? Like, what's the deal with this 'Mysteries of Chinatown' tour anyway? Does he know about Lo Pan and the Wing Kong and all that beforehand? It's never really explained, is it? Maybe I'm overthinking it, but it just feels like there's a missing piece there. Like, what's the tour actually about? Does anyone ever actually take the tour? Is it just a front? I need answers! Someone tell me I'm not crazy and that they've wondered this too! Or maybe someone has some behind-the-scenes info that explains it all. Let me know what you think!