I hit an odd, though not critical bug in the display of assembly language code on the question Disassembler for intel 8080. There's a block of assembly code where the format is:
opcode operand1 operand2 comment
for each line. The poster originally formatted it using a block quote, but noted that it didn't look right. I changed it to be formatted as code, but saw something odd.
When I first did it, I hadn't lined up the comments. So I went back and lined them all up. While editing, the live preview showed that the first 3 lines had one less space before the comment than was actually there. This was odd, but I thought I'd just add a space to those lines. In the live preview they now lined up. But when I pressed the button to save the edits, suddenly they had 1 extra space in the actual display of the assembly code and they no longer aligned.
So I edited it again and removed the extra space. Sure enough the code in the editor looked fine, but the preview showed 1 too few spaces on those lines. But when I saved it, they came back and everything aligned.