Sorry I am actually using the L1T product now, however I there is a similar problem although it starts after Band 49 (radiance gain = 0.025) because after this band is Band 71 (0.0125), then Band 50 (0.025), Band 72(0.0125) , Band 51 (0.025) etc as shown below.

Is your data in TIFF or HDF format?
Did a .hdr file come with your Hyperion data? If so, can you move the .hdr out of the directory and open the L1R (for HDF) or MTL (for Geotiff)?

I downloaded the L1T in GeoTIFF format, which I opened through the MTL_L1T.TXT file and subset through the use of an ROI.

Hyperion is an unusual sensor with lots of band overlap. The HDF and TIFF products open with bands in different order. With HDF, we try to put them into wavelength order but with GeoTIFF, they are in the original (overlapping) order. With the HDF file, I show bands 1-59 as 0.025 which are all VIS-NIR up to 950nm; bands 60-70 as 0.0125 which are above 950nm; 71-81 as 0.025 which are again in the VIS-NIR; then 82-242 as 0.0125 which are SWIR. This looks correct to me.
I think the tutorial may be outdated (from 5.2) as we made adjustments to the wavelength assignments for Hyperion.

So it is still ok to use the GeoTIFF for analysis? Also, when I create a spatial subset from an ROI, how do I then re-open that subset once I have closed ENVI?

Thanks.

Yes, it should still be ok. I believe the scale factors are properly set for the bands, it is just that they are ordered differently in the MTL file. Be sure to perform radiometric calibration on the data which should remove the bad bands.
How did you create the spatial subset? Did you create a new file from the subset? If so, you can just open it (it will be in ENVI format which is a .dat + associated .hdr) and all the metadata should still be present.

I created it through ROI Tool Options > Subset Data with ROIs > Ouput result to File

There is a.hdr and .enp file and a file with no extension, is that the .dat?

yes, it is a flat binary file and the header (.hdr) is the metadata file used to import it.