At the end when Lisbon, Jane, and Trina are at the juvenile center, the position of Trina's ponytail changes between shots.
No protection detail would ever be one person, alone, with not only a protected witness, but his daughter and the prosecuting ADA in the house.
For precisely the reasons shown, there is always at least 2 people per shift.
A witness is never guarded by only one agent, there should be at the very least two.