What happened to the people at the museum?

[The Dark Knight]

The novelisation doesn't confirm or deny. It just states Vicki hopes the people are only unconscious.

Bearing in my mind how callous The Joker is I don't see why he'd use 'non lethal' gas to knock out the other patrons.  Even if he did surely some of the people sustained life-threatening injuries as a result of falling unconscious.

I agree. I don't think the fact people didn't laugh to death rules out a fatal gas.

[Cobblepot4Mayor]

Sorry to throw "a spanner into the works" here guys but I can tell you in my very old Batman movie sticker album (which also tells the complete story of the film) it was firmly described the gas was of the sleeping variety.

I personally believe The Joker killed them. Not surprised with the confusion though. It's possibly the most "Adam West" the Tim Burton Batman film ever got. The TV show was constantly gassing people with colored smoke and safely knocking them out left, right and center. Twas a joy to behold (in a film claiming to distance itself from the days of the pop art Batman) allowing itself to incorporate a brief tribute. But you can also view them as using that moment to put a "deadly spin" on a famous Adam West element.

Might be worth posting that album up if anybody's got it. Anyone remember it? I think it was British based and came from a company I believe called "Merlin", which did a lot of sticker based movie merchandise in those days. It even features a two page section exclusively focused on Prince with pictures from I think his "Lovesexy" tour and the full lyrics of "Batdance". I never sadly completed my album.

[Travesty]

But were these cards official, or did they just hire a random writer for these cards, and have him interpret his own ideas onto the back of them?

Personally, I always saw it as him killing everybody. That's all he was about in this movie.

[DocLathropBrown]

Not to mention that the copy writers for that kind of promotional stuff would likely have wanted to downplay the viciousness of that act by the Joker, given that the products were for children. Remember that the film was highly controversial for its time, even being banned in certain countries for its darkness!

Given that he kills so many other people throughout the film, creatively it makes no sense for the Joker not to be killing in that one scene. I'm sure if you were to ask Burton, Hamm, Keaton or Nicholson.... they'd tell you that the idea was that he murdered the whole lot. I'm sure it was the implication that the filmmakers had in mind.

[JokerMeThis]

I remember looking at the script for this scene and I believe it said that the people fell unconscious. It's been a long time though and I don't remember any more details.

[Slash Man]

I originally thought they were killed, but the script actually leans more towards knocking out.

TRAYS OF FOOD CRASH TO THE FLOOR as WAITERS pass out.
ART LOVERS drop forks, go face down in their pasta salad.

Vicki hurriedly fits the gas mask over her nose and mouth.
Within seconds, she's the only one conscious in the room.

The use of terms like "pass out" and only describing them as unconcious.

[The Laughing Fish]

I originally thought they were killed, but the script actually leans more towards knocking out.

TRAYS OF FOOD CRASH TO THE FLOOR as WAITERS pass out.
ART LOVERS drop forks, go face down in their pasta salad.

Vicki hurriedly fits the gas mask over her nose and mouth.
Within seconds, she's the only one conscious in the room.

The use of terms like "pass out" and only describing them as unconcious.

Keep in mind though that filmmakers can change ideas when they begin to shoot scenes. Scenes aren't always tied up to whatever was originally intended in the script. For example, TDK's shooting script had Harvey Dent grinning with approval when Gordon revealed he was still alive; implying that the two had secretly worked together and deceived everybody in order to set the Joker up in a trap. But in the final cut of the film, we see Dent looking rather surprised and we aren't given any inferences that he knew anything about Gordon faking his own death or his plan to capture the Joker.

I still think that two of the restaurant guests who collapsed on their desserts with their eyes wide open must have meant that the Joker's poisonous gas was lethal.