At Chuck and Sarah's rehearsal dinner, Big Mike asks Morgan how he got injured and he replied Wii tennis. This could have been a reference to Chuck's star Zachary Levi's injury while actually playing Wii tennis - he had to get 14 stitches.
The Amacayacu mine entrance is actually one of the Bronson Canyon Caves in Griffith Park near L.A. This location has been used in scores of movies since the 1920s and was the Batcave in the 1960s TV show Batman (1966).
The buyer that Grimes has to impersonate is called Ettore La Barba. In Italian La Barba means The Beard.
At 13:46, the security camera shows Mary Bartowski (Linda Hamilton) performing chin-ups using an up-ended bed as the bar, referencing Sarah Connor (Linda Hamilton) in Terminator 2.
When Morgan is practicing his Italian accent in Castle, one of the examples he uses is "It's a me a Mario!" This is a reference to Super Mario 64, and is what the title character says on the home screen before the player presses Start.