There are 1 train company operating 4 routes - RE5, CNL 1258, ICE28, IC26. The cheapest train costs $37 and is 2h 45min.
There are 4 ways to travel from TXL to RLG. 2 flights, 4 buses, 5 trains and 1 by car are possible between the two areas. The by car from TXL to RLG is the cheapest and fastest. The train operated by DB running from Berlin Hbf to Mistorf is the most convenient.