An attempt was made in the early 90's to re-release 'Underdog' in syndication but because of the drug culture at the time all references to the "secret energy pill" were removed. Without them the cartoons did not make sense and were quickly pulled. This is a little ironic since the original reason the pills were added was to encourage children to take their vitamins.
The series originally aired with a four-part "Underdog" episode running complete in its 30-minute time slot. All current TV prints are a compendium of two related shows, "The Underdog Show" and "Tennessee Tuxedo And His Tales" (but shown under the "Underdog" title), with each of their segments mixed into each 30-minute episode. Some TV prints open with a segment "introducing an exciting scene from today's 4-part episode...", but instead of going into the preview the main credits roll. The end credits use titles from both "Underdog" and "Tennessee Tuxedo" shows.