My group is currently at a place in a Pathfinder campaign where they want to transport an incorporeal spirit using a bag of holding. According to the bag of holding rules, there is nothing that would prevent this from happening that I can see.
Aura moderate conjuration; CL 9th
Slot —; Price see below; Weight see below
Description
This appears to be a common cloth sack about 2 feet by 4 feet in size. The bag of holding opens into a nondimensional space: its inside is larger than its outside dimensions. Regardless of what is put into the bag, it weighs a fixed Amount. This weight, and the limits in weight and volume of the bag's contents, depend on the bag's type, as shown on the table below.
Bag Bag Weight Contents Limit Contents Volume Limit Market Price
Type I 15 lbs. 250 lbs. 30 cubic ft. 2,500 gp
Type II 25 lbs. 500 lbs. 70 cubic ft. 5,000 gp
Type III 35 lbs. 1,000 lbs. 150 cubic ft. 7,400 gp
Type IV 60 lbs. 1,500 lbs. 250 cubic ft. 10,000 gp
If a bag of holding is overloaded, or if sharp objects pierce it (from inside or outside), the bag immediately ruptures and is ruined, and all contents are lost forever. If a bag of holding is turned inside out, all of its contents spill out, unharmed, but the bag must be put right before it can be used again. If living creatures are placed within the bag, they can survive for up to 10 minutes, after which time they suffocate. Retrieving a specific item from a bag of holding is a move Action, unless the bag contains more than an ordinary backpack would hold, in which case retrieving a specific item is a full-round action. Magic items placed inside the bag do not offer any benefit to the character carrying the bag.
If a bag of holding is placed within a portable hole, a rift to the Astral Plane is torn in the space: bag and hole alike are sucked into the void and forever lost. If a portable hole is placed within a bag of holding, it opens a gate to the Astral Plane: the hole, the bag, and any creatures within a 10-foot radius are drawn there, destroying the portable hole and bag of holding in the process.
So can this happen? The incorporeal creature is willing, by the way.
There's absolutely nothing stopping it from happening. The incorporeal creature will enter the open bag, step into an extra-dimensional space, and the bag will be closed. The only problem will be the lack of oxygen since incorporeal creatures still have to breathe AFAICT.
Incorporeal is a subtype so the need to breathe depends on that. If the spirit is a ghost or petitioner then it is a non-issue.