The motel scenes in which Julia holds Tom captive that are supposed to be set in California have non-American electrical outlets, revealing the scenes' Mexican location.
After Julia goes to the bus station to retrieve the money, she steals a car after noticing policemen keeping guard next to hers. When she arrives in the desert and finds Tom unconscious, she wakes him up by splashing him with water from the bottle that was in her original car.
When Julia finds Tom unconscious in the desert, she gets out of the car and shouts Tom's name several times as she runs towards him. Listen carefully, and you'll hear Tilda Swinton calling out 'Tom' with her real life English accent instead of her character's American accent.
Elena: You know, the people here, they're really nice to each other. You can feel safe here. And we can help you. I know you. You live right across from me, we're neighbors.