Sarah appears to have an unexplained costume change from attire appropriate for the time back to her modern clothes. In DVD commentary, it is suggested she changed in the TARDIS and not showing it was an error, though only the Doctor is shown visiting the TARDIS. However, she got her native clothing from Sir Edward's castle and she had returned there, giving her opportunity to change back into her 20th century attire and return the other clothes. As she is returning to Irongron's castle to defeat Linx, it would be natural to think she would also be expecting to return to her own time soon with the Doctor and want her original clothes again.