All bricks have the mold pip on the short side and a flowrib.
Red: scratched numbers (I found 1 to 16)
Transparent: the G seems to have been punched into the mold, showing the punch surface around the letter (1 to 24).
The yellow and blue bricks (1 to 24) are more similar, the bricks from these molds are difficult to separate.
[Original post and comments on Flickr.]