1 Minnesota Jones: There's the labyrinth entrance. Looks like they've left a thread so they couldn't get lost inside. {pointing at the thread Dr Smith has tied to a nearby bush and trailed into the labyrinth}
2 Sallah: I know! Let's untie it and wind it up as we follow them in!
3 Prof. Jones: Well that sounds like a splendid plan to me!
4 Minnesota Jones: They get this from hanging around with you, don't they boy?

When I wrote this, and as it sat in my scripts file for several weeks before I took the photos and put the strip together, the punchline was completely different. Instead of Minnesota Jones' last line, I originally had Monty saying:

I can't believe I'm hearing this...

But as I was adding the speech balloons and got to the last one, I realised that just wasn't funny any more. So I upped the ante a bit and wrote a biting line for Minnesota.

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2014-02-03 Rerun commentary: The labyrinth set was only ever built as just enough walls to see and give the impression of various corridors and doors. It would have been cool to build an actual entire labyrinth out of LEGO bricks, and arrange the various scenes within it as they navigated their way through. But (a) I barely had enough of these grey LEGO walls to pull off this visual illusion of a grander labyrinth around them, and (b) building something a lot bigger and more permanent would have caused some interesting discussion with my wife.

Hint, by the way: If you are about to enter a labyrinth legendary for its ability to not be gotten out of, don't untie the string.

Also, given how many classic Dungeons & Dragons dungeons are labyrinth-like, and have the additional properties that walls shift and you can unknowingly get teleported to random other places within it, it's amazing how many adventurers rely on drawing a map as their only means of finding their way out again, rather than the expedient of trailing a string behind them. (Of course, trailing a string behind you is essentially advertising to any monsters wandering around: "Food, this way!!")