The title doesn't appear on screen until the end.
On the receipt during the end credits, Seth Rogen's name appears next to 4.20. A reference to cannabis.
At the start of the end credits the crew has joking references attached to their 'product': Pilar Flynn--"USDA Select More or Less;" Kevin Pavlovic--"Caution: Eye Irritant;" Salma Hayek--net weight "Sorry. Never ask a woman her weight!;" Jonah Hill--"100% Not Vegetarian;" etc.