Besides, there's no sign that it's got any of the complex stuff... all it does is launch, go straight up, and explode. No need for guidance systems, liquid fuel engines, any of that stuff. Just a big firework (aka, a solid fuel rocket). A bit of a stretch for 1893, but not an impossible one.
Indeed -- Congreve and improved Hale design rockets of up to 60 lbs weight were used from early in the Victorian era. Scaling up shouldn't have presented much of a problem if all it had to do was go up and explode. Probably no telemetry or ground-based guidance of course, although Hertz had already demonstrated the potential of radio waves by 1895. I think I spotted what might have been intended to represent a difference engine lurking behind the organ.