The tag implication #66179 mismatched_genitalia -> anatomically_inaccurate is pending approval.

Reason: The wiki page for anatomically_inaccurate cites mismatched genitals as a type of anatomical inaccuracy.

According to the mismatched_genitalia wiki:

Probably does not apply to mythological and other fictional species (such as dragons). It will depend on how closely they resemble a real life species or a character's established genitals (if any).

That "probably" and "depend" indicates it can, even if only sometimes. Then tags like anatomically_inaccurate or anatomically_accurate wouldn't always apply since fictional species aren't real to declare any kind of (in)accuracy. Similarly, it says

Characters that possess genitalia from multiple species serve as an exception to the above restrictions.

So a dragon with a canine_penis and a humanoid_penis would be allowed the tag, since genitalia from multiple species is an exception to the restriction on fictional species. And dragons, like other fictional species, shouldn't be tagged for anatomical (in)accuracy.