Factual error: When they are being kicked out of a Corpus Christi dance club in 1961 for singing do-wop, someone screams "We want to hear Tejano.". Tejano music was born in 1972 in Alice, Texas. In 1961, the correct term was "Tex-Mex" which later became "Chicano" which is now known today as "Tejano". The word "Tejano" was not known in 1961.
Factual error: The queen's maid tells Brown that the queen is currently reading 'Lord Tennyson.' That would be difficult in 1864, as Tennyson did not accept a peerage until the early 1880s.
Factual error: During Howard's "Thank You" speech to New York he gives NYC the gift of a live performance by AC/DC. The year was 1985. As the band takes the stage and launches into "You Shook Me All Night" we see Phil Rudd on drums. Rudd had quit AC/DC two years earlier and was replaced by Simon Wright. (Rudd returned in 1994, hence being part of the band when the scene was filmed).