No, they aren't, but it's easy to see how they would sound similar to the ear of a Japanese speaker.
In American English, a /t/ between two vowels is realised as an alveolar flap, transcribed like this : /t̬/. It's a light tap sound, when the tongue briefly touches the ridge behind the teeth on the roof or the mouth.
It's understandable that a Japanese speaker might interpret this alveolar flap as an 'l' or an 'r', as the nearest Japanese sound to 'l' and 'r' is also an alveolar consonant ( the sound at the beginning of 'roku', for example). But it's actually a kind of light 'd' sound. In fact, one of the names for this allophone is 'quick d'. It certainly sounds like a 'd' to native English speakers with other accents.
Take a look at this page below. It's quite helpful in explaining the different ways that 't' can be realised: