Danger of Fused Neutrals
Check to make sure that the neutral conductor does not have a fuse installed inline. If the neutral conductor is connected to a fuse that blows, the system will appear to be turned off because electricity will not flow, but the load side of the system will still be energized. Someone could accidently come into contact with energized electrical components because they mistakenly think the system is not energized.
Floating Neutral Bus Bar
The primary difference between a service panel and a sub-panel is that the sub-panel, the neutral bus bar floats. This means that the bus bar is electrically insulated from the metal cabinet. The degree to which a bonded neutral in a sub-panel is dangerous depends on who you ask. It's recommended that you not state the degree to which a bonded neutral is serious unless you feel that you can explain your reasoning clearly and logically in court. It's best just to state that it is improper, recommend correction by a qualified electrical contractor, and move on.
Isolating Neutrals at the Neutral Bus Bar
At the service panel, neutral and grounding conductors can terminate on the same bus bar, but multiple neutral conductors must not terminate together under one screw because this complicates the isolation of circuits. For neutral conductors… only one per screw is allowed.