The pointers to guards' bitmap data are off by two bytes, so not only do the guards' graphics not line up with their masks, but they're also drawn too low by one row:

You can easily spot this in the game by turning left-right while wearing the guards' uniform.

The third frame of the dog animation ("dog facing bottom right 3") has two stray pixels turned on at the bottom-left of the image by the dog's rear legs. This isn't a problem with the sprite itself but its definition in the sprite_stove sprites array which defines the sizes of, and pointers to, all of the game sprites. It lists it as having a height of 15, but the data is actually only 13 rows high. The result is two rows of data are lifted from the next frame's data.

The fix is to POKE CEA0,13.

There is a related glitch here in that all of the prisoner sprites are mis-specified: they're all one row too high. This doesn't produce a visible glitch however.

Spotted by Bandit on WoS forums.