I know it's been a while and I'm posting on a very quiet thread here, but I got into this comic only recently, so I figure it's worth mentioning:
113.jpgg is, as mentioned upthread, a typo, and you can find the actual image by taking off that extra g, and visiting 113.jpg.
As for 133 - it, like many other panels in the comic, is actually a png, not a jpg, and so the link is presumably supposed to point to 133.png (which is an available file) instead of 133.jpg (which isn't).
The comic's numbering seems to be a bit weird sometimes - pages 109 and 165 are repeated as -1 and -2 for each, and I can't seem to find anything numbered 137. It's hard to tell if there's supposed to be another page between 136 and 138, but there could be. I was surprised by how hard this sort of thing can be to notice; on my first read through the comic, I didn't see page 113 or 133, and never suspected that they were missing, either.