Three codes were hidden in the HTML source of the IN WHICH PAC FACES THE HEAT post on the Investigate Ingress blog.

[1] sayexla3wpmc77s3

[2] 94030791979403979k02080907949j920594030f029k92

[3] bq5t6ueac3hrn5s

Code #1

Observations

16 characters with the right amount of numbers for a valid passcode

Code #2

Observations

An old roman emperor should put everything in the right range

Code #3

Observations

15 characters with the right amount of numbers for a valid passcode, but with a twist this time