Bad Export for You: The third special never got a solo release. If you want it on DVD, you have to buy the whole trilogy.
Edited for Syndication: In addition to the Same Language Dub, the first two specials have been aired as a single hour long (i.e. 45 minutes + advertisements) special in America, cutting around 15 minutes of material from the original versions. One of the most obvious edits is the removal of the scene where Robbie actually discovers the vikings in the first place. The US DVD is uncut, alternate credits aside, and has the original British dialog as an alternate audio track. Prior to CBS getting the rights, the first special had aired on Fox Family uncut.
This would also count as a Compilation Movie, as it uses a single credits sequence and adds a "A couple years later" caption to the opening of the second short, although the individual titles still appear (even when the scene it originally appeared in is cut). This version also includes footage of the US cast recording their lines during the credits, which isn't included on the US DVD release.
Keep Circulating the Tapes: In the US, at least, the first two specials were absent from television for years before finally returning to CBS in 2016.
Orphaned Reference: The British version of 'Legend Of The Lost Tribe' includes footage of the actors recording their lines during the credits, which is removed on the US DVD (which contained both voices). However, the audio of these lines still appears on the British audio track, which must seem odd for anyone not familiar with the original version.
Talking to Himself: In the original, impersonator Alistair McGowan voices both Alan Snowman and Des Yeti.