Despite its consistent praise, the show was part of a big studio, airing on a network aimed at kids. As a result, there were tons of studio notes on what wouldn't be allowed.
Those who worked on the show revealed the supposed nine big taboos: guns, drugs, breaking glass, alcohol, smoking, nudity, child endangerment, religion, and strangulation.
However, the show did include some of these elements, such as guns and Batman breaking through windows. These apparently were allowed after much argument.
The studio compromised. Batman could crash through other things, like brick walls, and the show could have unrealistic, joke, or otherwise fantastical weapons.