The 5-6 time-zone differential between Barcelona and New York, does not relate to the relatively large day/night timezone differentials shown in several scenes in the film. In some instances, the flows of the day, appear reversed from what they they would actually be.
Speaking about Cristina's photography the narrator says that Maria convinces her to use an older camera and she would set up a darkroom for her, etc. implying it would be a film camera. It's clear she continues to use a digital camera and she does not look through the viewfinder but the LCD screen of a digital camera and the photo she just took is on the screen.
As Cristina walks into Juan Antonio's house for the first time, she is wearing a white blouse with long sleeves. As we first see her, one sleeve (the viewer's left) is three-quarters length and the other is rolled up at the elbow. After a very slight scene shift, but with no time passing, we see Cristina with both sleeves rolled up.
(at around 1 min) After Maria Elena moves in, they are having breakfast outdoors. Juan Antonio serves coffee for Cristina and takes the sugar bowl which is in front of Maria Elena in the foreground, and puts it in front of Cristina. The sugar bowl travels back and forth (three times) during the scene.
When Vicky and Juan Antonio have dinner the behind shots and face shots of Juan Antonio do not match. In face shots he is leaning forward and his head to the side. On behind shots he sits straight upright.
Cristina gets sick when they are at Oviedo for the week-end. The doctor goes to her hotel room and advises her to rest and tells that she became sick because of her ulcer. In another scene, someone asks for a painkiller and she takes aspirin from her purse, despite the fact that aspirin worsens ulcers. However, she could merely carry aspirin in the event family/friends need it, which is what happens during the movie.
During the flights in the Piper twin-engine aircraft, the airspeed indicator reads zero and the attitude indicator is flagged, showing that it is unpowered. This would indicate that the aircraft is not running and is sitting on the ground.
When Juan Antonio receives a phone call in the middle of the night, he reaches over and turns on a lamp. The lamp turns on, then the wall lights up a split second later, revealing the wall's glow to be coming from another light source.