Background noise with shotgun mic. Be care if you use a shotgun mic, and your shot picks up footsteps, machinery, or music in its background. Make sure to listen with headphones, and flip your decible setting from 0 to 10 or 20 to reduce high background noise. Having a lapel mic can eliminate most of these hazzards.
Not enough sun on the front of the building. If you do not have the luxury of setting up the shoot at a time when the sun is shining on the front of the client's building, you should return to shoot the building with the sun shining on its face, or ask the client to shoot that one scene with their iPhone and send it to you using a service like Box, or Dropbox.
Shooting your narration in a busy location. Shooting the narration in a room busy with people can be both intimidating and exciting to the client. Find out what the client prefers. Shooting the narration in a back office is not ideal. It's worth it to have the depth of the open floor of the business as the backdrop in the narration. If it is too difficult to shoot with people in the background, plan a second visit, plan the shoot near closing time, or shoot after hours and have the client shoot some busy scenes with his or her iPhone and send via a service like Box or Dropbox.
Technical issues that cause lost footage. There are many factors that can cause lost footage: Background noise, loose sound connection, a bumped setting, low battery, running our of memory, electrical interference, poor lighting, not hitting the record button hard enough... Always double-check that your footage came out good before you leave the shoot.