To emphasize the need for vigilance for potentially dangerous objects introduced during a scanner installation. Installation of an MRI is a routine process, with approximately 10,000 units installed in the United State Alone [1]. It is tempting to assume that installation will proceed seamlessly. Unfortunately, after a recent major hardware upgrade, we found a number of metal objects that had the potential to detract from the performance of the machine or, in the worst case, pose a hazard to personnel. We illustrate the process of discovering these potential hazards to prevent problems among other sites.A Siemens Trio underwent a major hardware upgrade to a Prisma (Siemens Medical Solutions) in the winter of 2014. This upgrade entailed replacement of nearly every aspect of the scanner hardware except the cryostat. Due to the extent of the hardware changes, the magnet was ramped down during the upgrade. After installation but before ramp-up of the magnet, we inspected the area underneath the floor of the imaging room. To accommodate cabling for fMRI stimulus and other equipment, the imaging room has a removable floor with a ~0.5 meter gap beneath (figure 1). A brief inspection of this gap (figure 2) revealed a significant amount of debris. Two MR physicists subsequently spent ~10 man-hours exhaustively cleaning every square foot of the gap for debris.Figure 3 illustrates a sampling of items found. A number of the items are magnetic (figure 4). Among the objects was a knife (figure 5) which, in addition to being magnetic also poses a severe hazard should it become a projectile. In addition to the items shown, there were a number of disconnected cables left behind.The potential hazard of projectiles is well-recognized. However, the presence of non-magnetic metal objects and loose cables may introduce intermittent spiking that can detract from imaging quality. The problems we encountered were exacerbated by the removable floor, which hides the debris. Rooms without such a floor may not be at as much risk.