We assume that if we are looking at a lateral view of a tadpole, and anterior is to the right, that it is indeed the right side of the animal, and that the image has NOT been flipped.
Like wise, anterior to left is showing the left hand side of an embryo.
This is REALLY important for genes that are expressed asymmetrically ( eg in alimentary system of heart), as many researchers use Xenbase to validate asymmetrical gene expression patterns . If you are considering flipping images, we would strongly urge you NOT to, but instead photograph both side of the embryos.
Some might say that flipping images is tantamount to faking your data. So please, don't do it.