The "kangaroo care" that Bailey advises Karev to preform with the baby is a real and recognized beneficial technique to improve developmental care. It has been shown to improve heart rate, temperature and blood pressure regulation, immune system response, and weight gain. It's named after the similarity to how marsupials carry their young.
The episode title, Invest in Love, is a song by Beckah Shae.
Izzie Stevens did not appear in this episode, but she is credit for it
Erica Gimpel (Bethany Anderson) played the mother to Arizona's patient Wallace. In Veronica Mars (2004) Erica played the recurring role of Alicia Fennel, mother of the main character Wallace Fennel (played by Percy III Dags).
Although the main credits appear at the sides of the screen, like they usually do, the one that says "An ABC Studios Production" appears at the middle of the screen, something we haven't seen since the early season 1 episodes.