Sacha

Other mistake: When Mr. Freeze threatens to freeze all of Gotham City, he has a big snowglobe in his hand. He freezes the snowglobe, then shatters it in is hand. When he crushes it open with his hand, the inside of the snowglobe is empty. There is no water, frozen or unfrozen, that comes out of the snowglobe when it breaks. (01:23:50)

Continuity mistake: When Freeze freezes Frosty while he holds a newspaper, Frosty's position and the way the newspaper folds change between shots. The position and number of icicles around him also change drastically.

Sacha ★

Continuity mistake: Ivy extends the threefold invitation to the Botanical Garden event, but a shot later, it's folded and held against her chest. (00:38:00)

Sacha ★

Revealing mistake: After Batman slides and kicks Freeze, there's a protruding lump under his clothes where the safety cable holding him was.

Sacha ★

Deliberate mistake: At the beginning when Batman and Robin are facing Freeze, Robin arrives and crashes through the wall with his motorcycle and leaves a shape in the wall that a motorcycle could possibly make. But, the next shot after Batman looks where Robin is still flying and about to land on his motorcycle, there is a huge bat shape in the broken wall. Obviously done for campy effect, but still a mistake regardless.