Editing trailers with multiple formats, such as widescreen and portrait orientations, is a common challenge, and mistakes can occur if not handled carefully. One mistake needs to be paying attention to the composition for each format, which can lead to awkward framing and distracting visuals. Another area for improvement is using consistent resolution, which can affect the quality of the final product. Editors should ensure that the trailer looks sharp and professional across all formats. By avoiding these common mistakes, editors can ensure that the trailer remains polished, regardless of the platform on which it's viewed.