Inspector Ruiz is often seen with agents of the local police of Madrid. Terrorist attacks in Spain are investigated by the National Police Corps, however.
None of the 17 universities in the Madrid autonomous region has the name "University of Madrid".
Most Basque characters don't have Basque names or surnames, but Castilian ones. Some of these names are also misspelled: Orozco (an actual Basque surname) as "Orasco" and De la Sierra as "De la Serra". The Italian name Gina, though popular in Latin America, isn't a common name in Spain. As we are told that both of Gina's parents are ETA members, it would make more sense that they would give her daughter a Basque name.
The Spanish government has not any "file of voices" of Spanish citizens.
Though a mobile phone can be turned into a radio transmitter, it cannot be opened at a distance.
The Basque characters don't speak Basque. Only Spanish and English with strong Latin American accents.
Several grammatical errors in the terrorist list of demands reveal that it wasn't written by a native Spanish speaker. Notably, the word "alambre" (meaning "wire", the object) is used as a verb.
The map showing the pretended independent Basque Republic doesn't cover the area in which Basque language is spoken nor the regions claimed by ETA. Moreover, Euskara means "Basque language", not "Basque Country", whose correct form in Basque is Euskadi.
Col. Eli McNulty claims that the Basques "want a state, like the Serbs and the Kurds and the Palestinians". Serbia won her independence from the Ottoman Empire in 1878 and the Serbs where the dominant ethnic group during the time that this country was part of Yugoslavia (1918-2003). In 2005 the Serbs already had their own state - and their own state only, much to their chagrin.
The US ambassador to Spain says that 173 people were killed in the 2004 train bombings in Madrid. In reality, they were 191. This is corrected in the European Spanish dubbed version.
Since ETA isn't a political organization, but a terrorist one, it doesn't make political meetings. It's possible that the character was actually talking about its alleged political branch, Batasuna, but even in this case it is very unlikely that such meeting would take place in Barcelona, because Batasuna is a regional (and now illegal) political party in the Basque autonomous region. The European Spanish dub changes Barcelona to Bilbao, one of three province capitals in the Basque Country.
Miguel says that he's done with painting walls and that they will never succeed unless they start killing people. Gina is shocked. When this episode aired, ETA had already killed over 800 people.