At the beginning of the movie (at 04:08), Carlos crosses off the rectangle for Sunday (Domingo) the 18th in the rightmost column of a preprinted calendar page that is missing the 26th of the month. It contains seven columns starting with Monday and running through Sunday. Below Sunday the 18th at the far right, Sunday the 25th can be seen, but at the far left, underneath the box for Monday (Lunes) the 19th is a box containing 27 followed to the right by boxes containing 28, 29, 30, and 31, Thus the 26th of the month has been left off the calendar since the 27th should be Tuesday (Martes).
While looking through a box of Carlos' belongings he kept in her office, Doña Carmen finds a small photo album with the note "trabajos Mamá / Señora Maqjuensi / 323 2175021 / Señora Esnaide / 323 3961825" (at 1:29:56; in English the first line is "Mom works" or "Mom's jobs"). Doña Carmen presumably calls one or both of these numbers but is shown speaking on the phone to Señora Snyder (at 1:30:12) who wasn't listed on the note. (The spellings of womens' names shown in the note are undoubtedly phonetic-isms for "MacKenzie" and "Snyder", meaning that "Señora Snyder" actually IS listed on the note.)