Integrated intensity maps of the CO 14–13 line at 185.99 μm (top panel), the [O I] line at 63.18 μm (middle panel), and the OH line at 163.13 μm (bottom panel). The solid contours show the line emission in steps of 5σ, 8σ, 11σ, 14σ, 15σ (top panel); 35σ, 55σ, 75σ, 95σ (middle panel); and 5σ, 10σ, 15σ, 20σ, 25σ (bottom panel). The dotted contours show the extent of the continuum emission at the 5σ level. The magenta and blue stars show the DR21-1 core (Cao et al. 2019) and the center of the explosive outflow at (α, δ)_{J 2000}=(20^h 39^m 00^s.8,+42^∘ 19^′ 37^′′.62) from Guzmán Ccolque et al. (2024); the magenta arrows indicate the outflow direction from HCO⁺ (Skretas et al. 2023) and the white crosses (×) the H₂ peaks (Garden et al. 1986). The maps were convolved with the beam size at 186 μm, represented by the orange circle at the map. For comparison, the original beam size at 63 μm is also shown. The blue dashed grid lines show the area of ten boxes used for the analysis of the far-IR emission along the outflow direction (see Sect. 3).