Luggage and bags:
Clothing/Shoes/Weather Gear: If you feel like crawling thru the tunnel system, just wear old clothes , as you will be sure to get dirty and sweaty. Better bring additional clothing to change afterwards. Cheap gloves and some kind of knee protection would be good as well as firm shoes
Toiletries and Medical Supplies: Humid tissues as well as a towel for cleaning up after crawling are essential. Some band aids for for cut fingers or bruised knees are surely welcome
Photo Equipment: Flash or light necessary when crawling the tunnels. Cameras should be equipped with a wide angle lens 24-28 mm.
Miscellaneous: If crawling the tunnels bring a torch. (Head torch best) with spare batteries
Water or other drinks
Th Cu Chi Tunnels is located in a jungle area and is hot and humid for most of the day and hence, it is best to wear light colored shirts and walking shorts instead of jeans. having a comfortable footwear such as rubber shoes or crocs or sanuk or flip flops is better then wearing boots or leather shoes as the terrain here is so uneven and hard. also have you sunglasses and hats ready as to minimize glare and sun burn.
Photo Equipment: as usual, my tip will be to bring a really light but powerful ultrazoom camera like the modern pocket ultrazoom cameras or if you like using raw images, the light micro 4/3 cameras or the PN cameras which have the DSLR qualities but without the bulk.