 In the DVD documentary The Thunderbirds Companion , Anderson explained how a rise in filming costs had made overseas distribution revenue even more important and essentially caused Thunderbirds to be made " as an American show " . During the character development and voice casting process , the Andersons ' main priority was to ensure that the series had transatlantic appeal , thus increasing the chances of winning an American network deal and the higher audience figures that this market had to offer . Scripts were typed in American English and printed on US @-@ style quarto @-@ size paper . 
 In the DVD documentary The Thunderbirds Companion , Anderson explained how a rise in filming costs <a href='been_done' title='1'><mark>had</mark></a> made overseas distribution revenue even more important and essentially caused Thunderbirds to be made " as an American show " . During the character development and voice casting process , the Andersons <a href='null_genetive' title='2'><mark>'</mark></a>main priority was to ensure that the series had transatlantic appeal , thus increasing the chances of winning an American network deal and the higher audience <a href='uninflect' title='3'><mark>figures</mark></a> <a href='null_relcl' title='4'><mark>that</mark></a>this market had to offer . Scripts <a href='uninflect' title='5'><mark>were</mark></a> typed in American English and printed on US @-@ style quarto @-@ size paper . 
In da DVD documentary TdaThunderbirds Companion , Anderson explained how a rise in filming costs done made overseas distribution revenue even more important and essentially caused Thunderbirds to be made " as an American show " . durin the character development and voice casting process , thdandersons  main priority was to ensure that thedaries had transatlantic appeal , thus increasing the dances of winning an American network deal and the higher audience figure this market had to offer . Scripts was typed in American English and printed on US @-@ style quarto @-@ size paper .