Translation issues in the script?

I quickly realised that this was a Spanish film made in English, but what really surprised me were the apparent "mistakes" in the English dialogue.

It appears that the director Rodrido Cortes also wrote it, whether he wrote it in Spanish or English I don't know but there are some very obvious "mistakes", for example when someone asks about Buckley's whereabouts they say, several times "He's with Silver".

This struck me as odd because while this usage might apply to a social situation, say Buckley and Silver are friends and they're at a bar together hanging out, it really doesn't fit the scene at all. Buckley is at his show investigating him, he isn't "with him". If this wasn't strange enough two different characters use this wording in the film.

"When the power of love overcomes the love of power, the world will know peace." - Jimi Hendrix