This is based on the television series. In the original children's books, Clifford never talked.
The trailer opens with the music "Main Title (Trailer Music)" by APM Film Orchestra, which was also featured in the trailer for "Dinotopia: Quest for the Ruby Sunstone (2005)".
Unlike in Clifford the Big Red Dog (2000) where the eyes of the characters aside from Clifford had black dotted eyes, their eyes in this film are now all white with sclera.