Seems crazy to me at times.
'You were standing with your legs apart rather than together, penalty!' Easy 3 points.
You've got it. Here's a list of the most common ones, as I recall. There are others.
"Coming in from the side", penalty.
"Side parting on the wrong side", penalty.
"Not entering via the gate", penalty.
"Leaving the bog door open", penalty.
"In front of the back foot", penalty.
"Standing on one foot", penalty.
"Visible dissent", penalty.
"Visible panty line", penalty.
And that's before you get to scrummaging. That's where it gets really complicated.
"Boring in", penalty.
"Boring off", penalty.