At the end of this episode, Bones says that the idea of soul mates originated with Plato. The story she refers to is from the Symposium, written by Plato. But the story of the round people with four arms and four legs is not told by Socrates (whom always holds Plato's theories in his writings), but by Aristophanes - a comedian playwright, who often made fun of Socrates in his plays. So Plato lets him tell this ridicules story (which has absolutely no counterpart in the Greek myths), to display Aristophanes' ignorance and lack of philosophy.
When Booth takes Eddie's and McKenna's guns and checks whether they are loaded, as a routine security measure. When he does it, he keeps pointing the barrel at other people (Brennan and McKenna respectively). This is a major violation of gun safety, something experienced agent like Booth would have never done.
In season 4's episode where the team attends a funeral for a fallen colleague and sneak him to the lab, they use Angela's Toyota Matrix. In this episode, we see Angela driving a Sienna. Although there is no way of determining the time between the episodes, it's unlikely that Angela traded cars so soon. This would be a result of Toyota obviously sponsoring the vehicles for the show where in most shows when cars are driven the brands are never mentioned and insignias are usually hidden. Dr Brennen also drives a Prius, also made by Toyota.